Search engines I use the Internet but have trouble finding subjects which others routinely retrieve from the Web. I have been told that the secret is in the choice of the proper search engine. These are the servers where data is stored. There is no library with a catalog file to tell us what is available. If there was, it would become obsolete at once.
New sites appear continuously around the world, while others die from lack of attention.
They consist of keywords gathered from Web documents and catalogued on a computer. Some engines have accumulated 40 million pages of references, and there are several dozens of these engines. Many of them work tirelessly, snooping through all available sites on the net. They are known as spiders, or crawlers. How the search algorithm has been defined determines how much useful data they bring back.