Advertising terms explained in plain English

CPM, CPC, programmatic, DSP, the CAP Code: this glossary sets out what the terms in your ad platform dashboard and your agency's emails actually mean, with a UK-relevant example alongside each one so the definition means something.

Once the terms make sense, check whether your test results do: try the A/B Test Significance Calculator Ready to put a number on a campaign? The Ad Budget Calculator gives you a starting figure

What this glossary covers

Advertising has its own vocabulary, and most of it gets thrown at business owners without explanation. A media planner will mention CPM (cost per thousand impressions) or ask whether you want to buy through a DSP (demand-side platform) as if everyone already knows what those mean. This glossary sets out the terms you're likely to meet when planning, buying, or reporting on advertising in the UK, so you can follow a conversation with an agency or a platform rep without nodding along blindly.

Where the terms come from

The entries pull from a few different corners of the industry, because a business running its first campaign might encounter any of them within a week of starting out.

Pricing and measurement: CPM, CPC (cost per click), CTR (click-through rate) and the other figures used to work out what a campaign is actually costing and doing.
Digital buying: programmatic advertising, DSPs, paid social, and the mechanics of how ad space gets bought and sold in real time.
Regulation: the ASA (Advertising Standards Authority), the CAP Code, and the rules that govern what an ad is allowed to say.
Traditional and out-of-home: OOH (out-of-home advertising) and the terms that still get used for billboards, transport ads, and print.

Reading a definition

Each entry follows the same shape: the term, a plain explanation of what it means, and, where it helps, a note on why the distinction matters in practice. A definition that only tells you what something is not leaves you to work out the rest yourself, so the entries here are written the other way round, starting from what the thing actually does.

When a definition isn't enough

A glossary entry answers what a term means. It won't tell you how much a Google Ads campaign should cost for a business your size, or what the ASA expects from an influencer post, and those questions deserve fuller answers than a single paragraph can give. The advertising guides go into that depth, and the UK advertising rules guide is a reasonable next stop if a compliance term is what sent you here. If a term relates to budgeting or benchmarking, the ad budget calculator puts the numbers to work, though like any calculator it depends on the figures you feed it and can only be a starting point for planning.