Wolfram|Alpha launched on May 15, 2009. Many early users expecting it to work like a search engine complained that the site wouldn't return results to some simple queries. But unlike Google -- and other search sites -- Alpha isn't an attempt to catalog the world's information. Instead, it's what Wolfram Research calls a computational knowledge engine.
Traditional search engines crawl the Web for sites and add them to their directories. Algorithms built into the code that powers these search engines rank pages higher or lower based on several factors. One is the number of people who click on the link from the search engine results page (SERP). Another is the number of third-party Web sites that link to that site. If you create a public Web site, there's a decent chance it'll end up on a search engine without your having to do a thing to get it listed - as long as there are links to it from other sites
Wolfram|Alpha doesn't scan the Web for material. Instead, it relies on licensed databases and content entered, tagged and cataloged by Wolfram Research employees. According to the company, there were more than 10 trillion individual chunks of data on the Alpha servers at the time of the site's launch [source: Wolfram Research]. Wolfram Research employees vet all information to ensure its accuracy before it's added to the Wolfram|Alpha databases.
To get that information, a person types a query into the search box on the Wolfram|Alpha home page and presses the equals sign to the right -- the equals sign is a clue that there's math going on in the background. Alpha then looks searches for corresponding data in its databases.
Results can be quite simple: Enter the name of a city, and you'll get the time of day and weather information, as well as population and elevation above sea level. Input several city names and you'll get a table that enables you to compare them. If you type in the name of an animal, you'll get the average size, alternate names, scientific name and even a breakdown of its taxonomy. Again, if you ask Alpha for the names of different animals, you'll get a table comparing them, and you'll even see how they're related taxonomically.
Scientific and mathematical problems are easy for Alpha to handle. In fact, you can ask the computational knowledge engine to derive a calculus problem and not only will it tell you the answer, it will also show you what steps are required to solve it.
But remember, Wolfram|Alpha isn't a search engine, which means that if you want to find pictures of celebrities, the cheapest price on a flight to London or articles written about a specific topic, you need to use a search engine. Alpha is designed for you to ask it a question and get a factually correct answer, along with a visual interpretation of that answer.