When you search for something, you want the answer, not billions of webpages. So Google ranking systems sort through the hundreds of billions of webpages in the Search index to give useful and relevant results in a fraction of a second.
These ranking systems are made up of a series of algorithms that analyse what it is , that people are looking for and what information to return to searchers. And Google has evolved Search to make it more useful, the company has refined the algorithms to assess searches and the results in finer detail to make Google services work better for customers.