What Is On-Page SEO?

On-page SEO is the work done on a website itself to help search engines understand what each page is about and to help users find what they are looking for. It is distinct from off-page SEO, which involves signals from outside the site such as links, and from technical SEO, which involves the underlying infrastructure. On-page SEO is the content layer — what the page says, how it says it, and how it is structured.

It is also the part most businesses get wrong first, because it looks straightforward and is easy to do badly.

Most businesses think on-page SEO is about adding keywords to their existing content. It is not. It is about ensuring that every signal on the page answers the same question: what is this page for, and who is it for? Generic content with keywords inserted is still generic content. Google reads intent, not keyword density.

The core elements are best understood as the Content Signal Stack — six on-page signals that Google reads to understand what a page is about: URL, Title Tag, H1, Body Content, Internal Links, and Image Alt Text. Each element reinforces the others. A strong title tag on a weak body is a mixed signal. All six aligned around the same topic is a clear one. In practice, pages where the title tag, H1, and first paragraph all reference the same primary term consistently outperform pages where those three elements point in different directions — even when the body content is longer and more detailed.

Title Tag: The clickable headline in Google search results. One of the strongest on-page signals. It should describe the page accurately, include the primary keyword, and be written to encourage clicks. Practical limit: around 60 characters before Google truncates it.

Meta Description: The paragraph beneath the title in search results. Does not directly affect rankings but affects click-through rate, which affects rankings indirectly. Around 150 characters, specific rather than generic.

H1 Heading: The main heading visible on the page. One per page. It tells both Google and the reader what the page is fundamentally about.

Body Content: The substance of the page. For Google to rank a page for a search term, the page needs to actually cover that topic in sufficient depth — answering the questions a searcher has when they type the query.

Internal Links: Connections between pages within the same site. They help Google discover content, understand relationships between topics, and distribute authority.

Image Alt Text: The written description attached to images. Google cannot interpret images directly. Alt text tells it what an image contains and serves an accessibility function.

URL Structure: A URL like allertondigital.co.uk/services/local-seo tells Google and the user exactly what to expect. A URL like allertondigital.co.uk/page?id=47 tells neither.

None of these elements require specialist tools. They require decisions — about what each page is for, who it is for, and what it needs to say.