It’s the <title> apparently.
RE: w3.org/QA/Tips/good-titles
Minimal requirements of a validly coded title
In theory, technically, HTML still works just by going straight into a <p> tag for example, without strictly needing a <html> tag, <head> tag or <body> tag.
However, in order for a <title> tag to be honoured reliably, it should be placed within a <head> tag which itself is placed within a <html> tag; meanwhile the page’s main content should be placed within a <body> tag that’s also placed inside the <html> tag, just after where we’ve already placed the <head> tag.
Thus, a minimal HTML document with valid <title> and main content would look like this:
<html>
<head>
<title> (title content) </title>
</head>
<body>
(main content)
</body>
</html>
See also
- FAQ: Where are the most influential places to put keywords?
- See how the Page Title Tag stacks up against other places to put keywords for the purpose of dictating which keywords a page should rank highly for!