Type a word into the search box, jump to a letter, or filter by discipline: SEO, Google Ads, Meta Ads, analytics and tracking, local marketing, ecommerce, and legal and compliance among them. Each term has its own page with a short definition, how it works, why it matters to a business like yours, the common mistakes and what to do next.
How to use this glossary
Search is the quickest route. It matches the term name and its other names, so typing “CPC” or “cost per click” finds the same entry. If you only half remember a word, jump to its first letter instead and scan the list.
The discipline filters help when you are reading one kind of document. Working through a Google Ads report, filter to Google Ads and you will see the vocabulary that report is likely to use. Reading a website quote, try Websites and Tech or SEO.
Every term page follows the same order, so you can stop as soon as you have what you need:
- A one or two sentence definition at the top, which is often enough.
- How it works, for when you need to understand the mechanism.
- Why it matters for a UK business, which is the part that tells you whether to care.
- Common mistakes and how to act on it, for when the term points to something that needs fixing.
The quick facts box on each page lists other names for the term, how technical it is, what it affects and where you can see it, such as GA4, Google Search Console or Meta Ads Manager.
Terms that are easy to mix up
A lot of confusion in reports comes from two terms that sound alike but measure different things. Get these pairs straight before you judge any report.
| Often confused | The difference | Why it matters |
|---|---|---|
| CPC and CPA | Cost per click is what you pay for a visit. Cost per acquisition is what you pay for an enquiry or sale. | Cheap clicks that never become customers are expensive. Judge spend on the second number. |
| Impressions and reach | Impressions count every time an ad was shown. Reach counts the people who saw it at least once. | A report can show large impressions from a small audience seeing the same ad over and over. |
| Google Ads conversions and GA4 key events | Both count actions such as form submissions, but GA4 now calls them key events and credits them using its own rules. | The totals rarely match, and that is usually expected. My article on why GA4 and Facebook report different conversion numbers explains the gap. |
| ROAS and profit | Return on ad spend compares revenue with ad cost. It ignores your product costs, delivery and VAT. | £4 back for every £1 spent can still lose money on a 20% margin. The ROAS and break-even calculator works out the return you actually need. |
| Domain Authority and Google ranking | Domain Authority is a score made by an SEO software company. Google does not use it. | A rising score is not a ranking improvement. Ask what happened to the searches that bring you customers. |
Using it to read a proposal or report
When a proposal or report lands, go through it once and underline every term you could not explain to a colleague. Look each one up before the meeting rather than during it. You will ask better questions, and you will notice when a document leans on jargon to fill space.
Then, for each number in the report, ask which of three things it describes: visibility (people seeing you), activity (people visiting or clicking) or outcomes (enquiries, bookings, sales). Good reporting connects the first two to the third. If a monthly report is all visibility and activity, ask how many enquiries or sales the work produced and how that was measured.
If you are choosing who to hire, my guide on how to choose a digital marketing agency or consultant covers the questions worth asking alongside the vocabulary.
Why the definitions are written this way
I wrote every definition myself, for a UK reader. That means British spelling, prices in pounds, and UK context where it changes the answer: cookie consent under UK GDPR and PECR, the ASA and the CAP Code for advertising claims, and Google Business Profile as it works for UK businesses.
I have kept the definitions practical rather than academic. Where a metric comes from a third-party tool rather than from Google or Meta, the page says so. Where a term is mostly vendor language with little effect on results, the page says that too, so you can stop worrying about it.
If a term is missing
A glossary explains single words. To see how they fit together, the longer guides are a better place to start: the SEO guide for UK small businesses, the Google Ads guide and the guide to Facebook and Instagram ads each walk through their subject in order.
If you cannot find a term, or the definition does not answer your question in the context you met it, send me the term and where you saw it. Tell me the sentence it appeared in if you can, because the same word can mean different things in an SEO audit and an ad account.