Page titles are important because they help a user navigate their browser. Most users have multiple tabs open at once. It’s easier to jump between pages if each page title is unique. It’s also helpful to have the unique portion first, usually the name of the page.
<title>Page Titles - 18F Accessibility</title>
The title for this page is ‘Page Titles - 18F Accessibility’. The first half is the name of this page and the second is the name of the site.