Search engines are the most commonly used tool in finding information on the Internet. Search engines collect, organise, search for and display web pages. Google and Yahoo! are examples of search engines.

When searching in search engines you search in the engine's database, you do not search the web pages in real time. Even the most comprehensive search engines only cover some parts of the web, so if you only use your favourite search engine you will miss out on relevant websites. Read more about search engines

Search engines are suitable when searching for

• Narrow topics and well-defined research questions
• Specific search words and precise concepts

Keep in mind that

• Search engines only cover a small part of the Internet
• They lack “The Invisible Web”
• They cover some academic databases and e-journals, but not in full like academic databases
• They are not big enough (cover only parts of the Internet). Some subjects are very poorly covered
• Search results are not evaluated, they are presented according to mathematical rules for relevance evaluation
• It varies how often they are updated. Sometimes they can be several months behind

Use search engines if you have a specific question!

Scientific search services index material that comes from universities, research institutes, academic publishers, etc. Google Scholar, Scopus and Scirus are examples of scientific search services. Here non-scientific pages are filtered out - for example, a search for “Dolly” will retrieve information about the cloning of the sheep Dolly - not about Dolly Duck or Dolly Parton.

Use specialised search engines if you are looking for scientific information!

There are several encyclopedias available online. A new, interactive kind is:

Wikipedia, a web based international encyclopedia. It is a wiki, meaning that everyone can edit its content and that it can be updated rapidly. For new terms and definitions it is the best web site around. The English Wikipedia is usually the most up-to-date one. Keep in mind that the content is not always quality approved, unlike more traditional encyclopedias. If you do decide to use Wikipedia as a source, you should supplement with at least one more source.

There are thousands of databases with specialised information on the web. The bases may be produced by organisations or individuals, and are often available to anyone. Others are delivered by commercial suppliers, and require subscription and login.

Spiders and robot programs cannot find this information, and that is why it is often referred to as “deep Web” or “The Invisible Web”. This part of the Internet is much larger than the retrievable part ordinary search engines can find. Very few people who search for Internet sites know that they miss out on this information. Read more about the deep Web

Lately, the large search engines have begun to index parts of scholarly databases and e-journals, so that you can find some scholarly articles.