Searches using wolfram alpha
Wolfram|Alpha is a computational knowledge engine for computing answers and providing knowledge; it is not a search engine.
Wolfram Alpha computes answers and relevant visualizations from a knowledge base of curated, structured data that come from other sites and books. The site uses a portfolio of automated and manual methods, including statistics, visualization, source cross-checking, and expert review. The curated data makes Alpha different from semantic search engines, which index a large number of answers and then try to match the question to one.
Wolfram Alpha can only provide robust query results based on computational facts, not queries on the social sciences, cultural studies or even many questions about history where responses require more subtlety and complexity. It is able to respond to particularly-phrased natural language fact-based questions such as "Where was Mary Robinson born?" or more complex questions such as "How old was Queen Elizabeth II in 1974?" It displays its "Input interpretation" of such a question, using standardized phrases such as "age | of Queen Elizabeth II (royalty) | in 1974", the answer of which is "Age at start of 1974: 47 years", and a biography link. Wolfram Alpha does not answer queries which require a narrative response such as "What is the difference between the Julian and the Gregorian calendars?" but will answer factual or computational questions such as "June 1 in Julian calendar".
Mathematical symbolism can be parsed by the engine, which typically responds with more than the numerical results. For example, "lim(x->0) (sin x)/x" yields the correct limiting value of 1, as well as a plot, up to 235 terms (as of 2013) of the Taylor series, and (for registered users) a possible derivation using L'Hôpital's rule. It is also able to perform calculations on data using more than one source. For example, "What is the fifty-second smallest country by GDP per capita?" yields Nicaragua, $1160 per year.
It's now availble through Vicki. Just ask her anything and she'll run it through WolframAlpha !