What are title, description and keyword elements?  What purpose do they serve?  Where do they appear on your site?

What will be an ideal response?

The title, description, and keyword elements help visitors find your Web site.

The title is not displayed on the page itself; it appears in the title bar of the visitor's browser and as the title in a browser's list of favorites or bookmarks if a visitor has added it to that list.

The description and keywords are used by some search engines to help determine what your site is about. Search engine results often display the contents of the title element as the link to your site, so it should be reader-friendly and descriptive.  Search engine results also often display the contents of the description element as the description below the link, so this should be a brief, interesting explanation of what visitors can find at your site.  It should motivate them to visit.

Keywords are a list of terms, separated by commas, that describe the content of your site. These words are the terms your site visitors are likely to enter in a search engine.