The Internet would not be the force it is at present without powerful search engines such as Google. Incidentally, as Google is by some margin the most popular search engine, and therefore the most important, we will use it for our discussion throughout the rest of the book.
It is critically important for search engines to provide relevant results; otherwise, people will use another service. A search engine's survival, therefore, comes down to how efficiently they can provide results that best meet a user's requirement. In order to survive, a search engine needs to do the following two things very well:
Index as much content as possible
Return highly relevant results
By indexing as much online content as possible and making it available to everyone, Google allows people to find what they are after. But there's a catch. As there is so much content online, Google needs a way to decide which content is the best and most likely to give people what they want.
These dual...