On-page SEO: the signals a page sends about itself

On-page SEO is work on what a page says about itself through its own markup and text: headings, address, the text behind its images, its links and its place in the site's structure. A reader and a search engine meet these signals first, and Google's advice for them is the one it gives for all of Search: write for people.

What counts as on-page

On-page signals are the ones you set inside the page and its address, without asking anyone else. This section covers six of them.

• Headings

  The outline of the page, from the H1 down, that lets a reader scan and lets a machine see the structure.

• The URL slug

  The readable part of the address that says what the page is before anybody opens it.

• Alt text

  The text that stands in for an image when it cannot be seen, read by screen readers and by search engines alike.

• Anchor text and internal links

  The words that link one page to another and the paths they make through a site.

• Breadcrumbs

  The trail that shows where a page sits in the site's hierarchy.

• The XML sitemap

  The list of addresses a site gives search engines so nothing important is missed.

What lives elsewhere on this site

Some page signals have sections of their own here. Titles, descriptions and canonical tags are covered under meta tags. Machine-readable markup about the page, such as JSON-LD, is covered under structured data. Language versions are covered under hreflang, and moved addresses under redirects.

What this site does not cover is whether a page can be crawled or indexed at all: robots rules, noindex and indexing status belong to BotBridge, which documents how pages reach crawlers.

What Google says about these signals

Google's guidance on these elements is consistently practical. Its SEO Starter Guide, last updated on 2025-12-10 and checked on 2026-10-12, asks you to "provide headings to help users navigate your pages," calls alt text "a short, but descriptive piece of text that explains the relationship between the image and your content," and describes link text as "the text part of a link that you can see."

None of these is presented as a lever that moves a page by itself. Each helps a reader understand the page, and helps Google understand it in the same way. That is also Google's position on newer AI search features: its guide to generative AI features, last updated on 2026-07-10, calls optimizing for them "still SEO."

How to approach the section

Start with what is broken rather than with what could be polished. A page without an H1, images without alt text, slugs made of ID numbers and pages no link points to are faults a reader notices. Fix those first, then refine the wording.

Keep each signal true to the page. A heading that promises what the section does not deliver, alt text stuffed with keywords and anchor text that says "click here" all describe something other than what is there, and that is the opposite of what these signals are for.

A checklist for one page

A single page can be checked in a few minutes with nothing but the browser and its view of the source. Work down the list and note what fails.

• One H1 that names the page

  Find the main heading in the source and check that it says what the page is, and that lower headings follow in order without skipping levels.

• A readable address

  Read the URL aloud. Words separated by hyphens pass; a string of ID numbers or parameters does not.

• Alt text where images carry meaning

  Every image that informs has a short description of what it shows in context; purely decorative images have an empty one.

• Links in and out

  At least one other page on the site links here with words that describe it, and the page links on to related pages the same way.

• A place in the structure

  The page sits under a parent a reader can reach, shown by a breadcrumb trail where the site uses one, and it appears in the XML sitemap.

• Title and description present

  Both exist and describe this page, not the site; the meta tags section covers how to write them.

Each item on this list has its own page in this section or the next one. Run the list again after a redesign or a template change, since templates are where these signals most often break across many pages at once.

Fixing at the template, not the page

Most on-page faults are not written by hand; they are produced by a template and repeated on every page that uses it. A theme that renders the site name as the H1, a product template that leaves images without alt text, a CMS that builds addresses from database IDs: each makes the same mistake hundreds of times. Fix it once in the template and every page inherits the fix, then check a few pages of each type to confirm the change came through.

What this section covers

The pages below take the on-page signals one at a time: headings and the H1, URL slugs, alt text, anchor text, internal links, breadcrumbs and the XML sitemap. Each one covers what the signal is, what Google and the web standards say about it, and how to get it right on a real site.

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