Wolfram Alpha - whats this? are you thinking , Wolfram Alpha is just a engine to get answers for your questions and queries.
It was similar to Yahoo Answers , but the operation is totally different.
You can type formula,questions and anything in this search engine and get the answers.
For Example :
While I am searching , i typed " Where is Italy " , the other search engines display a list of sites related to Italy and we can select any link to see the description .
But Wolfram Alpha simply displays a world map and specified where is Italy.
Wolfram Alpha is also known as Knowledge Engine.
It works under the technique called AI(Artificial Intelligence). If you want to know how it was working, just goto www.wolframalpha.com and type any formula ,city name, dates,etc., to know about it.