Glossary

Drowning in acronyms

113
Terms and counting
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Jul 2026
Last updated

Today the world has become obsessed with acronyms and we are practically drowning in them. Here in the UK, people understood things like the BBC or ITV when it came to watching the television, or getting an MoT for your car to make sure it was roadworthy. But text messaging brought with it LOL, LMAO and an ever expanding list of terms for people who can't be bothered to type complete words.

I still prefer full words and write longhand, but then again, I always have a pad and pencil on my desk 😊 Oh yes, and then there are emojis, but that's an entirely separate topic.

To help us all navigate the ever growing landscape of acronyms, here's a glossary of common terms that we'll endeavour to keep up to date for us all.

Under the bonnet

Domains, hosting and the plumbing underneath

The parts nobody sees until they stop working. Most of these turn up in conversations about moving a website, changing email provider, or working out why something isn't loading.

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DNS
Domain Name System

The internet's address book. It turns a domain name people can remember into the numerical address a computer actually needs.

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IP
Internet Protocol

The numbering system that gives every device and server on the internet its own address.

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TLD
Top Level Domain

The bit at the end of a domain name. .co.uk, .com, .org and so on.

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URL
Uniform Resource Locator

The full web address of a page, including the protocol, the domain and the path.

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HTTP / HTTPS
HyperText Transfer Protocol / Secure

The language browsers and servers use to talk to each other. The S means the conversation is encrypted, which is now the baseline expectation for any website.

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SSL / TLS
Secure Sockets Layer / Transport Layer Security

The certificate and encryption behind the padlock in your browser. SSL is the older name that stuck, TLS is what's actually in use today.

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TTL
Time To Live

How long a piece of DNS information is cached before it's checked again. It's why domain changes sometimes appear instantly for you and an hour later for someone else.

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CDN
Content Delivery Network

A network of servers around the world that keeps copies of your site's files close to your visitors, so pages load faster wherever people are.

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VPS
Virtual Private Server

A slice of a physical server reserved for you alone, with its own resources. A step up from shared hosting.

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FTP / SFTP
File Transfer Protocol / Secure

Methods of moving files to and from a server. SFTP is the encrypted version and the only one worth using now.

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SSH
Secure Shell

A secure way of connecting to a server to run commands directly.

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ISP
Internet Service Provider

The company supplying your internet connection.

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VPN
Virtual Private Network

An encrypted tunnel between your device and the internet, often used to work securely from outside the office.

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SaaS
Software as a Service

Software you use through a browser and pay for by subscription rather than installing and owning outright.

The raw materials

The building blocks

The languages, systems and tools a website is actually made of. You don't need to know any of this to run a business, but it helps when you're deciding what to build on.

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HTML
HyperText Markup Language

The structure of a web page. Headings, paragraphs, images, links, and the framework everything else hangs on.

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CSS
Cascading Style Sheets

The presentation layer. Colours, spacing, typography, layout, and how all of it responds to different screen sizes.

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JS
JavaScript

The language that makes pages interactive. Menus, sliders, forms, animation, and increasingly whole applications.

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PHP
Hypertext Preprocessor

A long established server-side language. It's what WordPress is built on.

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SQL
Structured Query Language

The language used to ask a database questions and store information in it.

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API
Application Programming Interface

A defined way for two systems to talk to each other. It's how your website might pull live stock levels from a warehouse system, or push an order into your accounts package.

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REST
Representational State Transfer

A common, well mannered style of building an API. Most of the APIs you'll come across follow it.

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JSON
JavaScript Object Notation

A lightweight text format used to pass structured data between systems. Readable by humans, easy for machines.

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XML
eXtensible Markup Language

An older structured data format, still very much alive in sitemaps and feeds.

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CMS
Content Management System

The admin area that lets you edit your own website without touching code. WordPress is the best known example.

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WYSIWYG
What You See Is What You Get

An editor that shows content roughly as it will appear on the page, rather than as raw code.

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SSG / SSR
Static Site Generation / Server-Side Rendering

Two approaches to building pages. SSG builds them in advance so they're ready to serve instantly, SSR builds them on request. Both are quicker and safer than the old model of assembling everything on the fly, every time.

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SPA
Single Page Application

A site that loads once and then updates the content in place rather than loading new pages. Great for applications, not always the right choice for a brochure site.

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IDE
Integrated Development Environment

The software a developer writes code in.

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CI/CD
Continuous Integration / Continuous Deployment

An automated pipeline that tests changes and pushes them live, so releases are consistent and repeatable rather than manual and nervous.

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SDK
Software Development Kit

A ready made toolkit for building against someone else's platform.

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DAM
Digital Asset Management

Keeping logos, photography, documents and brand files organised in one properly managed place, so the right version is always the one being used.

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LMS
Learning Management System

A platform for delivering courses, training and assessments online.

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CRM
Customer Relationship Management

The system holding your customer records, conversations and sales pipeline.

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ERP
Enterprise Resource Planning

The larger back office system covering stock, finance, purchasing and operations.

Look and feel

Design and how people use your site

The vocabulary of design conversations. These are the terms most likely to come up while we're working through a project together.

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UI
User Interface

Everything a visitor actually sees and touches. Buttons, forms, menus, layout.

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UX
User Experience

How it feels to use. Whether people can find what they need, understand what's being asked of them, and get where they're going without friction.

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IA
Information Architecture

How the content is organised and labelled. Get this right and the navigation writes itself.

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CTA
Call To Action

The thing you want the visitor to do next. Get in touch, book a call, add to basket.

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RWD
Responsive Web Design

Building one site that adapts to every screen size rather than maintaining a separate mobile version.

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SVG
Scalable Vector Graphics

Images described mathematically rather than as pixels, so they stay sharp at any size. Ideal for logos and icons.

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PNG / JPEG / GIF / WebP / AVIF
Image formats

PNG for sharp graphics and transparency, JPEG for photographs, GIF for simple animation, WebP and AVIF for modern, smaller, faster versions of both. Worth knowing that not every platform supports the newer formats, which occasionally catches people out.

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RGB / CMYK / HEX
Colour systems

RGB and HEX for screens, CMYK for print. A colour that looks right on your monitor won't necessarily look the same coming off a printing press.

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DPI / PPI
Dots Per Inch / Pixels Per Inch

Resolution measurements. DPI belongs to print, PPI to screens, and the two get muddled constantly.

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WCAG
Web Content Accessibility Guidelines

The international standard for making websites usable by people with disabilities. Increasingly a legal expectation as well as the right thing to do.

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A11y
Accessibility

Not strictly an acronym. It's accessibility with the eleven middle letters replaced by a number, which rather proves the point of this page.

Search and ads

Being found

Search, advertising and the numbers people quote at you in meetings. This is where the acronyms get thickest, and where a fair few of them are quietly meaningless.

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SEO
Search Engine Optimisation

The ongoing work of helping search engines understand your site and helping people find it. Technical health, content, structure and reputation, all pulling in the same direction.

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SERP
Search Engine Results Page

The page of results you get after searching. Increasingly crowded with adverts, maps, answers and AI summaries before the actual results appear.

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SEM
Search Engine Marketing

The paid side of search. Usually used to mean advertising rather than organic listings.

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PPC
Pay Per Click

Advertising where you pay each time somebody clicks. Google Ads is the obvious example.

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CPC
Cost Per Click

What each of those clicks costs you.

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CTR
Click Through Rate

The percentage of people who saw something and clicked it. Useful for judging whether your search listing or email subject line is doing its job.

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CRO
Conversion Rate Optimisation

Improving the percentage of visitors who go on to do the thing you wanted, rather than simply chasing more visitors.

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GSC
Google Search Console

Google's free tool showing how your site performs in search, what it's being found for, and anything Google is struggling with.

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GA4
Google Analytics 4

The current version of Google Analytics. A rather different beast from the Universal Analytics that came before it.

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GBP
Google Business Profile

Your listing on Google Maps and in local search. Formerly Google My Business, or GMB, which you'll still see referenced everywhere.

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UTM
Urchin Tracking Module

The tags added to a link so analytics can tell you exactly which campaign, email or post the visitor came from. Named after a company Google bought in 2005, which is why it makes no obvious sense.

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E-E-A-T
Experience, Expertise, Authoritativeness, Trustworthiness

The qualities Google says it looks for when judging content. Not a score you can check, more a description of what good looks like.

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KPI
Key Performance Indicator

The handful of numbers you've agreed actually matter, as opposed to the hundreds a dashboard will happily show you.

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ROI
Return On Investment

What you got back compared with what you put in.

In the inbox

Email

Email has quietly become the most acronym-heavy part of running a business online, largely because keeping it working now depends on three DNS records most people have never heard of.

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MX
Mail Exchange

The DNS record that tells the world which server handles email for your domain.

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SPF
Sender Policy Framework

A DNS record listing who is allowed to send email on your behalf.

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DKIM
DomainKeys Identified Mail

A cryptographic signature added to your outgoing email that proves it genuinely came from you and hasn't been tampered with.

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DMARC
Domain-based Message Authentication, Reporting and Conformance

The policy that ties SPF and DKIM together and tells receiving servers what to do when something fails. It also reports back to you on who is sending email using your domain, which is often quite the eye opener.

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IMAP / POP3
Internet Message Access Protocol / Post Office Protocol

Two ways of reading email from a server. IMAP keeps everything in sync across your devices, POP3 tends to download and remove it. IMAP is almost always what you want.

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SMTP
Simple Mail Transfer Protocol

The protocol used to send email.

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ESP
Email Service Provider

The platform used to send marketing email to a list.

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EDM
Electronic Direct Mail

A marketing email sent to a list. Essentially a campaign send, dressed up in a three letter suit.

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CTOR
Click To Open Rate

Of the people who opened your email, the percentage who clicked something. A more honest measure of whether the content landed than click rate alone.

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MFA / 2FA
Multi-Factor Authentication / Two-Factor Authentication

Requiring something more than a password to log in, usually a code from your phone or an authenticator app. The single most effective thing most businesses can do to protect their email.

Ringing the till

Selling online

The eCommerce vocabulary, including the page types every platform assumes you already know and the product codes that quietly decide whether your listings appear anywhere.

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B2B / B2C / D2C
Business to Business / Business to Consumer / Direct to Consumer

Who you're selling to, and increasingly, whether you're selling to them yourself rather than through a retailer.

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PDP
Product Detail Page

The page for a single product. You'll also hear it expanded as Product Display Page, and very commonly as Product Description Page, which is close enough that nobody ever gets pulled up on it. Detail is the version most platforms and developers use, and it's the more accurate one: the description is only a part of what the page holds, alongside the imagery, variations, price, stock and reviews. Worth noting that outside eCommerce, PDP usually means Personal Development Plan, so context matters if you work anywhere near an HR team.

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PLP
Product Listing Page

The category or collection page listing several products, where people browse and filter before choosing one. Most analytics funnels are described as PLP to PDP to basket to checkout, so once you know these two, a lot of platform documentation suddenly makes sense.

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CLP
Category Landing Page

A category page with proper editorial content sitting above the products. Useful where a category needs explaining or positioning rather than simply listing.

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SKU
Stock Keeping Unit

The unique code identifying a specific product or variation. You invent it, it only has to make sense within your own business, and it's yours to control. Get the SKU right and everything downstream behaves. Get it wrong and nothing does.

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GTIN
Global Trade Item Number

The umbrella term for the barcode numbers that identify a product globally rather than internally. Unlike a SKU, you can't invent one. They're issued through GS1, and they identify the product itself no matter who happens to be selling it. UPC, EAN and ISBN are all GTINs, they just differ in length and origin.

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UPC
Universal Product Code

The twelve digit barcode number used mainly in North America.

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EAN
European Article Number

The thirteen digit equivalent used across the UK and Europe, and the one you'll see on most products sold here. Officially it's now a GTIN-13, but nobody calls it that in conversation.

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ISBN
International Standard Book Number

The thirteen digit identifier for books. It's a valid GTIN in its own right, which is why books slot into the same product data field as everything else.

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MPN
Manufacturer Part Number

The code the manufacturer uses for a part or product. It matters because when a product genuinely has no GTIN, Google and the marketplaces will usually accept brand plus MPN instead. If a Shopping feed is being rejected or an Amazon listing won't create, muddled identifiers are very often the reason.

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AOV
Average Order Value

The average amount spent per order.

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POS
Point Of Sale

The till system in a physical shop, which often needs to talk to the website.

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PIM
Product Information Management

A single source of truth for product data, feeding the website, the marketplaces and anywhere else the catalogue appears.

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PSP
Payment Service Provider

The company processing your card payments. Stripe, Worldpay, PayPal and so on.

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PCI DSS
Payment Card Industry Data Security Standard

The security rules that apply to anyone handling card data. In practice, a very good reason to let a proper payment provider handle the card details rather than touching them yourself.

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3DS
3-D Secure

The extra verification step your bank sometimes adds at checkout.

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RMA
Return Merchandise Authorisation

The process for handling returns.

Locked and fast

Speed, security and staying out of trouble

Performance measurements, the attacks they're worth protecting against, and the regulations that apply whether or not anyone told you about them.

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CWV
Core Web Vitals

Google's set of measurements for how a page actually feels to load and use.

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LCP
Largest Contentful Paint

How long until the main thing on the page appears.

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INP
Interaction to Next Paint

How quickly the page responds when somebody taps or clicks. It replaced FID, First Input Delay, in 2024.

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CLS
Cumulative Layout Shift

How much the page jumps about while loading. If you've ever gone to tap a link and hit an advert instead, that's a poor CLS score.

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TTFB
Time To First Byte

How long the server takes to start responding. Usually a hosting or application question rather than a design one.

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WAF
Web Application Firewall

A filter sitting in front of your site, blocking malicious traffic before it ever reaches your server.

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DDoS
Distributed Denial of Service

An attack that overwhelms a site with traffic from many sources at once until it falls over.

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XSS
Cross-Site Scripting

An attack that injects malicious code into a page other people then view.

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CSRF
Cross-Site Request Forgery

An attack that tricks a logged in user's browser into performing an action they never intended.

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SQLi
SQL Injection

An attack that abuses a badly written database query to read or destroy data.

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GDPR
General Data Protection Regulation

The data protection framework governing how you collect, store and use personal information. The UK has its own version post-Brexit, but the principles are the same.

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DPA
Data Protection Act

The UK legislation sitting alongside UK GDPR.

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PECR
Privacy and Electronic Communications Regulations

The UK rules covering cookies, marketing emails and electronic communications specifically. This is the one that governs your cookie banner.

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ICO
Information Commissioner's Office

The UK regulator responsible for data protection and privacy.

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T&Cs
Terms and Conditions

The bit nobody reads and everybody agrees to.

Everyday chatter

And finally, the ones that turn up in our emails

I did say I preferred full words. In fairness, so do most of these people, right up until they're typing on a phone.

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ASAP
As Soon As Possible

Which, depending on who sent it, means anything from "this afternoon" to "before you read this".

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ETA
Estimated Time of Arrival

When something is expected to land. The word estimated is doing a lot of quiet work here.

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EOD / EOW
End Of Day / End Of Week

A deadline, expressed vaguely enough to survive being missed.

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TBC / TBD
To Be Confirmed / To Be Decided

Nobody has decided yet, and possibly nobody has been asked.

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WIP
Work In Progress

Started, not finished, and shown to you deliberately at this stage.

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FYI
For Your Information

No action needed, but somebody wanted it on the record that you were told.

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ICYMI
In Case You Missed It

You missed it.

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TL;DR
Too Long; Didn't Read

A short summary at the top of something long. Occasionally the only part anyone reads.

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AFAIK
As Far As I Know

A gentle disclaimer attached to something about to be stated confidently.

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IMO
In My Opinion

Which it always was, with or without the letters.

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OOO
Out Of Office

Away, and hopefully properly away rather than checking email from a deckchair.

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N/A
Not Applicable

This question doesn't apply here. Occasionally used to mean "no answer", which is not the same thing at all.

Nothing here for that one

We haven't covered that term yet, which is genuinely useful to know. Tell us what you were looking for and we'll add it.

Suggest a term

If something's missing

Spotted one we've not covered?

This list will grow, because the acronyms certainly will. If you've come across something in a quote, a report or an email from us that made no sense whatsoever, tell us and we'll add it.

There are no silly questions here, only three letter answers.

Suggest a termStart a conversation

Or just reply to any email from us. We read them all.