Mamma.com is a "smart" metasearch engine — every time you type in a query Mamma simultaneously searches a variety of engines, directories, and deep content sites, properly formats the words and syntax for each, compiles their results in a virtual database, eliminates duplicates, and displays them in a uniform manner according to relevance. It's like using multiple search engines, all at the same time.

Created in 1996 as a master's thesis, Mamma.com helped to introduce metasearch to the Internet as one of the first of its kind. Due to its quality results, and the benefits of metasearch, Mamma grew rapidly through word of mouth, and quickly became an established search engine on the Internet. Mamma.com's ability to gather the best search results available from top search sources and to provide useful tools to its users has resulted in its receiving multiple Honourable Mentions in the Best Metasearch category in the annual SearchEngineWatch Awards.

Every time you type in a query at a metasearch engine, they search a series of other search and content sites at the same time, compile their results, and display them either by source or by integrating them in a uniform manner, eliminating duplicates, and resorting them according to relevance. It's like using multiple search engines, all at the same time.

By using a metasearch engine, you get a snapshot of the top results from a variety of search engines (including a variety of types of search engines), providing you with a broad scope of information. Metasearch engines are tolerant of imprecise search terms or inexact use of operators, and tend to return fewer results, but with a greater degree of relevance. They're best used when you've got a general search, as metasearch engines return broad results. Instead of returning every possible result that contains your search term, metasearch will return the most trusted results on the Internet for your search. Metasearch engines also allow you to compare what kinds of results are available on different engine types (indexes, directories, pay-for-placement, etc), or to verify that you haven't missed a great resource provided by another site, other than your favourite search engine (acting as a backup). Overall, they're a great way to save time and find exactly what you're looking for!

Our Ranking Algorithm: rSort
rSort works like a voting system for search results. The search engines Mamma.com queries often return duplicate results. Instead of simply eliminating the duplicates as many metasearch engines may do, we use this information to rank our results. Each duplicate search result is considered a 'vote' for that result. Pages with the highest number of votes go at the top of our result set (for the mathematicians in the audience, the method of voting we use is a simplified version of the "Condorcet Method", named after the mathematician Marquis de Condorcet who invented this voting procedure in the 18th century). One of the big advantages of this ranking method is the elimination of search engine spam.

Spammers often have difficulty spamming more than one engine at the same time, as different spamming methods must be used for each search engine. Spam results will tend to receive fewer votes from multiple sources. A spammer may have top ranking on one search engine, but they won't achieve it on Mamma unless they're able to spam ALL of our sources, an insurmountable task for even the best spammer.

Here are some interesting stats about rSort:

Some of the health sites we search are: http://www.WebMD.com http://www.MedlinePlus.com http://www.MedicineNet.com http://www.NHSDirect.com http://www.RXList.com http://www.Drugdigest.org http://www.MayoClinic.com http://www.HealthAtoZ.com http://www.Medem.com http://www.eMedicine.com http://www.HealthDay.com