Titles for Web pages are made with the <title></title> tag in HTML.There should be only one title per page, and adding extra titles is a Google don't that could penalize you.
The title is what you see at the top of your browser window when you look at a page. It's also what you see by default when you bookmark a Web page.
Why Do Titles Matter to Search Engine Results?
Nobody but Google knows the exact algorithms they use to determine where pages rank in search results. However, most experts agree that keywords in the title have a greater weight than keywords in the body text.
It's only logical that if a page has a title of "Homemade Apple Pie" that the page is more about homemade apple pie than it is about rolling pins or flour, even though those words may be mentioned more often in the page.
Google does keep track of titles and index them separately, because you can restrict your searches to Web page titles. It stands to reason that they index titles separately, because they weigh them separately.
What If Title Keywords Didn't Make a Difference?
It's possible that title keywords don't actually matter to how your pages rank. However, they do still matter in Google. Every time you search for anything in Google, the results are listed by title first. The worst thing you could do is have an untitled page, and the second worst thing you could do is have a title that has nothing to do with your content.
People are skimmers. In an information age, we tend to see a page full of search results, and we quickly scan the titles to find the results that are most relevant to us. The title is your first impression, so make it meaningful, make it relevant, and make it interesting.
You can learn more about HTML tags from the About Guide to Web Design.