If you need information, chances are Siri can help you find it. Apple currently enables Siri to search Google (or Yahoo! or Bing) for general information, and Wolfram|Alpha for computational knowledge. You can use Siri to find anything you would normally type into a web search box, only there's no typing needed. Just ask, and you'll get back everything from the latest celebrity gossip to the answers to that nagging math questions to a listing of the best free apps for your iPhone.
Siri can search the web using whichever search engine you've set as default in Settings, under Safari. Unless you've changed it, that's Google. Yahoo! or Microsoft's Bing are the other options.
If you don't want to change your default search engine, but still want to check a different search engine, Siri can do that too.
Siri also has Wolfram|Alpha built right in. That means Siri can help you get answers to everything from basic equations to more advanced computations.
If you still need help searching for information with Siri, or using any other Siri feature, head on over to our Siri Forum and ask away!