SEO Glossary: 280+ Search Engine Optimisation Terms Explained

If you’ve ever sat in a marketing meeting and felt like everyone was speaking a different language, you aren’t alone. The world of Search Engine Optimisation (SEO) is famously filled with acronyms, technical codes, and confusing jargon.

But here’s the secret: you don’t need a computer science degree to understand it. We’ve put together this comprehensive A-Z guide to break down over 280 essential SEO terms into plain English. Bookmark this page, it’s the only dictionary you’ll need to navigate the search landscape with confidence.

# (The Numbers)

301 Redirect: Think of this as a “Permanent Change of Address” card for a website. It automatically sends visitors and search engines from an old URL to a brand-new one forever.

302 Redirect: A temporary detour. This tells search engines that a page has moved for a little while (perhaps for a holiday promo), but it will be coming back to the original spot soon.

304 Not Modified: A message from the server saying, “Nothing has changed here since you last looked.” This helps your browser load the page faster using saved data.

307 Redirect: The modern version of a temporary redirect (302). It ensures that when a user is moved to a new URL, the technical way they requested the page stays exactly the same.

404 Error: The “Page Not Found” message. It happens when a link is broken or a page has been deleted, leaving the visitor at a dead end.

410 Gone: A more serious version of the 404. It tells Google that a page is gone on purpose and will never be back, so it should be removed from search results immediately.

500 Internal Server Error: A general “oops” message. It means something went wrong on the website’s server that prevented the page from loading.

502 Bad Gateway: This happens when one server on the internet tries to talk to another but gets an invalid response—basically a “wrong number” for servers.

A

Above the Fold: This refers to everything you see on a screen the moment a page loads, before you start scrolling. It’s the most important part of your site for grabbing attention.

Ad Keyword: A specific word or phrase that a business pays for so their advertisement shows up when someone searches for that term.

Adobe Analytics: A high-end tool used by businesses to track how people use their website and where their traffic is coming from.

Ad Rank: A score that determines where your ad appears on the page. It’s based on how much you bid and how good (relevant) your ad actually is.

Affiliate: A person or website that promotes someone else’s products and gets a small “thank you” payment (commission) for every sale they help make.

Ahrefs: A popular tool used by SEO pros to see who is linking to their site and to spy on what keywords their competitors are ranking for.

Algorithm: The complex “brain” of a search engine. It’s the set of rules Google uses to decide which websites are the best answers to your search.

ALT Text: A short description of an image hidden in the code. It helps people with visual impairments understand the picture and helps Google “see” what’s in the photo.

AMP (Accelerated Mobile Pages): A way of building websites so they load almost instantly on your phone by keeping the design very simple.

Anchor Text: The actual clickable words in a link. They are usually blue and underlined, and they tell you what the next page is about before you click.

Artificial Intelligence (AI): Technology that allows computers to learn and solve problems like a human. In SEO, it’s used to understand search intent and even write content.

Auto-Generated Content: Text created by a computer program rather than a person. While fast to produce, it usually needs a human touch to be truly helpful for readers.

B

B2B (Business-to-Business): A company that sells its products or services to other companies, rather than to everyday shoppers.

Backlink: A link from another website to yours. In the eyes of search engines, every high-quality backlink is like a “vote” that your site is trustworthy.

Black Hat SEO: Risky or “sneaky” tactics used to try and trick Google into giving a site a higher ranking. These can get a website banned if they are caught.

Breadcrumb: A small row of links at the top of a page (like Home > Shoes > Sneakers) that helps you see exactly where you are on a website.

Broken Link: A link that doesn’t work anymore, usually leading to a 404 error page.

The rest of the alphabet’s SEO terms can be found over on Dark Horse’s A-Z glossary of SEO terms.