Type your query, hit Return, and off you go. You can search for the name of a product, a person, a topic, a specific Twitter username, or a --a word with a pound sign (#) in front of it (such as: #io2011).

Hashtags on Twitter are akin to tags on or --they're a tool that grew organically out of the community as a way to tag a topic or event. You can click, or tap, on a hashtag on Twitter.com and most of its clients to see all other tweets that contain the same tag. You can also track hashtags, a technique that I'll get to in a moment.

A useful perk of search.twitter.com is that its search results page is fluid. Instead of merely giving you a static list of results at the time you ran your query, it will actually continue watching Twitter for mentions and alert you at the top of the page when there are more to view. Dedicated apps for the Mac, iPhone, and iPad often provide a continuously updating live stream of these search results.

One drawback of Twitter's search tools is that, because of the sheer volume of tweets its users generate, Twitter only provides access to a few days' worth of archives. Twitter recently published some : as of March 2011, users now create one billion tweets per week, or 140 million tweets per day. The company's search index simply cannot keep up with that activity, which is something Twitter has been working to improve for . In other words, our tweets are all still there; you just can't search much farther back than a few days until Twitter improves its search infrastructure.

Twitter recently as well as just text tweets. At press time, this feature was still rolling out--some users could see it and some couldn't.