Live search is a method of searching that finds matches as soon as you begin typing. For example if you were to look for the word 'glossary' you would begin by typing g, l, o which would immediately start finding results such as glove or gloat (assuming those words were on your site to begin with) as well as the word glossary.

The more letters typed would narrow the search results until just the results bearing the word 'glossary' appear. The advatage of live search is that search results appear immediately, and you are able to alter your search terms quickly as you see results pop up. It saves you from having to enter search terms, wait to view a results page, then go back and alter the terms.

If that's not enough, there is an advanced search that lets you enter sophisticated search queries that sort by content type, author, date and so on.