Search engines are web tools that enable users to find information on the Internet. They typically function by searching for keywords and returning a list of documents where those keywords are found (known as a search engine results pages or SERPs). SERPs can be comprised of different types of files, like images, web pages and videos.

Search engines are similar to web directories in that they can help you find a website of interest, but unlike web directories, they process information in real-time, using a web crawler with an automatic algorithm.

Below, you can read about what makes the world’s leading search engines stand out, as well as a few words on some less known alternative search engines.

1. The big 3: Google, Bing, and Yahoo!

Google

We’re going to lump these guys all in one for obvious reasons. You already know about them I suspect?

Google is undoubtedly the dominant search engine, with over 65% of the market share in the United States alone. Bing comes in second with about 17% of the market, while Yahoo! struggles to maintain around 11%. If you are an online entrepreneur interested in SEO, understanding the indexing algorithms of Google and Bing can be of great help in growing your website.

Google uses a number of algorithms to order search results, of which the oldest and most well-known is PageRank. It works by looking at the number of quality links to a page in order to determine how important that page is. Unfortunately, PageRank has gradually been devalued over recent years, as more and more companies attempted to sell high-PR links for SEO purposes.

Google has since reoriented toward other strategies to help push high quality sites to the top of its search results, including Google Panda, Google Penguin and now Google Hummingbird. The latter is Google’s most important update in years – it is an entirely new algorithm designed to provide users with a smarter, more human way of interacting with the search engine. Google Hummingbird can interpret complex queries rather than just simple keywords, and can connect concepts to their meanings for more natural search results.

While Bing uses a similar algorithm to Google’s PageRank, it looks at a metric called “click distance” to measure the distance of a webpage from its homepage. The underlying assumption here is that pages that are closer to the homepage are going to be more relevant to the search.

Since 2011, Yahoo! Search has been powered by Bing, although search results are not exactly identical between the two engines.

2. Ask.com

Ask.com

A search engine focused on answering questions, Ask differs from traditional questions-and-answer websites in that it does not rely only on members of a community to solve queries, but also uses expert websites to aggregate factual answers. For example, a question pertaining to science will produce a scientific answer, as well as links to scientific publications providing additional details.

Unfortunately, Ask has been heavily criticized for its infamous malware-like toolbar, which cannot be removed from the browser through a traditional uninstall function.

3. DuckDuck Go

DuckDuck Go

This search engine looks similar to Google, but functions in a very different way – it pulls information from multiple sources (including Wikipedia, answer engines like WolframAlpha, and partner search engines like Bing and Yandex in Russia), to create its own search results page. More importantly, DuckDuck Go is keen on privacy and does not record user information, which means that every person that searches for a keyword will get exactly the same results.

DuckDuck Go also comes with a suite of perks that make browsing a bit more interesting. For example, it’s Goodies section can deliver instant answers to a wide range of questions: you can use math goodies and tech goodies to quickly make complex calculations and measurements.

4. Blekko

Blekko

This search engine wants one thing and one thing only: to take Google on and win! To achieve this lofty goal, Blekko eliminates “content farms” (websites delivering large amounts of content created only to satisfy search engine algorithms), and instead uses slashtags to generate search results.

The slashtag system is meant to speed up browsing and enable a better categorization of searches. Predefined slashtags allow users to jump right into browsing; and after signup, users can create their own search categories to further eliminate potential spam. This feature has generated mixed responses in reviewers – while some view it as a quirky detail, others have criticized it for adding an unnecessary hurdle to browsing.

5. AOL Search

AOL Search

AOL Search is currently “enhanced” by Google, which means that Google administers, sorts and maintains most of AOL’s listings, although multimedia and other types of content are provided via other partners. Websites that make it into AOL’s search results are ordered by relevance only for quicker results.

What’s interesting about it is that it provides multiple search opportunities with select websites across the AOL network, and consequently can be used as a solid source of news, entertainment, opinions and digital information. Its “Set Your Location” feature provides quick access to general information about your area, including weather forecasts, hot venues and upcoming events.

6. GoodSearch

GoodSearch

GoodSearch is powered by Bing (through a partnership with Yahoo!). This search engine is rather unique, in that it allows users to support their favorite nonprofit organization or school, by performing ordinary actions like browsing, taking surveys, shopping online, and playing online games. 50% of the company’s advertising revenue is then donated to the causes chosen by GoodSearch users.

This simple yet ingenious idea has garnered massive support, and GoodSearch has managed to donate to more than 100,000 schools and NGOs over the last year. The search engine is also popular with celebrities like Jessica Biel, Jeff Bridges and Emily Deschanel, who have promoted GoodSearch in relation to causes they support.

7. Dogpile

Dogpile

As the name suggests, Dogpile is a metasearch engine that “fetches” the best results from various other search engines (mainly Google, Yahoo! and Yandex).

The interesting thing about this search engine is that it compares data from multiple sources, and then it decides which ones are the most relevant for your search. Consequently, the list of results it produces should be spam free and more comprehensive than what you would get by using any of its partner search engines separately. This approach allows you to save a lot of time browsing, and gets you the results you need in one user-friendly engine.