The title tag is the page title specified with the HTML <title> element. It appears as the clickable heading in search results, in browser tabs, as the bookmark name, and as the title when the page is shared on social media. It is the first thing read in a search result, and the decision whether to open the page is largely made here, which is why SEO practice treats it as a priority element to get right.

Google states that there is no limit on the length of the <title> element and explains that the title shown in search results is truncated as needed to fit the width of the device. There is therefore no official threshold of the form "up to this many characters and everything is shown". In practice, around 30 characters for Japanese and around 50 to 60 characters for English are often used as working guidelines, but these are rules of thumb from observing search results, and the same title is cut at different points on desktop and on a smartphone. Because truncation happens from the end, the safe approach is to put important words and the core message toward the front and use the latter half for supplementary text that can be cut without breaking the meaning. For example, in "Character Count Methods and Tips - Complete Beginner's Guide", the point still comes across if the trailing site name or qualifier is dropped.

The guidelines Google gives for writing titles include being descriptive and concise, avoiding keyword stuffing, not reusing the same wording across multiple pages, and writing the title in the same language and writing system as the page content. It also explicitly advises against titles consisting only of words that say nothing about the page, such as "Home" or "Profile". When a site name is included, appending it at the end in the form "| Site Name" or "- Site Name" is the widely used convention. The caveat is that the site name eats into the space available for the actual subject. On sites with a long name, the end of the subject is the first thing to disappear where truncation occurs, so whether to include the site name can be decided per type of page.

Google does not always show the configured title tag verbatim in search results. The sources it officially lists for generating the heading shown in results (the title link) are the content of the <title> element, the main visual title shown on the page, heading elements such as <h1>, og:title, other text made large and prominent through styling, other text on the page, anchor text on the page, the text of links pointing to the page, and structured data. In other words, rewriting is not an exceptional accident but behavior built into the system from the start. To reduce the chance of a rewrite, keep the <title> and the on-page heading consistent with each other, and avoid a state in which only the <title> carries the information while the body offers no clues.

Title tags and meta descriptions are often confused, but they play different roles. The title tag is the wording that becomes the search result heading and tells both search engines and readers what the page is about. The meta description is the explanatory text shown beneath the heading, and Google has stated that it does not use it for ranking. Both influence whether a user clicks, so the practical approach is a division of labor: state the topic in the heading and support it in the description. The Open Graph og:title can be set independently of the title tag to change the title shown when the page is shared on social media. However, since og:title is also listed as a source for the title link in search results, making the two differ widely can lead to the unintended one being picked.

From a character counting perspective, the title tag is one of the HTML elements where character limits are most consciously managed. Full-width Japanese characters and half-width Latin characters occupy different widths, so the same character count produces different display lengths. A title of 30 full-width characters and one of 30 half-width alphanumeric characters, for example, differ in width, with the latter fitting into less horizontal space. In a title that mixes full-width and half-width characters, the character count alone cannot tell you whether it will fit. In practice, a two-step approach is used: measure the length with a character counting tool, then check the cut-off point in actual search results or in a preview matched to the display width. What you count is the original text before truncation; if you judge by the truncated appearance, you will not notice that the site name or qualifier placed at the end has been dropped.