Controlling how search engines access and index your website

Via Googleblog: http://googleblog.blogspot.com/2007/01/controlling-how-search-engines-access.html
"I'm often asked about how Google and search engines work. One key question is: how does Google know what parts of a website the site owner wants to have show up in search results? Can publishers specify that some parts of the site should be private and non-searchable? The good news is that those who publish on the web have a lot of control over which pages should appear in search results."