The default search term operator is AND
You can use brackets, AND OR and NOT to improve your search. For example: C# AND NOT ( VB or SQL )
A query of a single * will return everything, filtered by any filters.
Search by Author: author:"author name"
Filter by tag: tag:C# or tag:(C++ or Java)
Wildcard search use: "?" or "*" eg. gr?d or gr*
In this video Zach shows you what you'll need to know to get this great feature working on your page.