Short answer
On-page SEO is everything you optimize on the page itself so search engines and AI assistants understand it and see it as the best answer. That includes the content, the title tag, headings, meta description, URL, images, internal links and structured data. The aim is a page that matches what the searcher wants better than any other.
The elements, roughly in order of impact:
- Search intent match: the page gives the type of answer the searcher wants, such as a guide, a comparison or a product.
- Content depth: it answers the main question and the follow-ups.
- Title tag and H1: clear, specific and close to how people search.
- Headings: a logical structure, often phrased as the questions people ask.
- Internal links: from related pages, with descriptive anchor text.
- Structured data: schema that labels the page type, FAQs, products or reviews.
- Media: compressed images with descriptive alt text.