The title tag is the <title> element in the HTML <head> — the text Google displays as the clickable heading in search results. It is the single strongest on-page SEO signal Google uses to understand what a page is about and which queries it should rank for.
Best practice in 2026: 50-60 characters maximum (Google truncates around 600 pixels, which varies by character width — keep it under 60 to be safe). Lead with the primary keyword, follow with a differentiator, end with the brand. Example: "Free AEO Audit — 99 Checks in 30 Seconds | SeoChatAI". The brand at the end builds trust but does not consume the keyword-prominent opening.
Title tags get rewritten by Google in roughly 20-30% of impressions when Google decides the title does not match user intent for the specific query. You cannot fully control this, but you can make rewrites less likely by writing titles that closely mirror the page's H1 and the queries you intend to rank for.
For AEO, the title tag also serves as the canonical name for AI-engine citation. ChatGPT, Perplexity, and Google AI Overviews all display the title (or a paraphrase) when citing your page. A clear, descriptive title earns more clicks from the AI citation surface than a clever or branded-only title.