Are you curious about "How Google works"? I found an interesting paper writen by Sergey Brin and Lawrence Page,the creator of Google. The paper titled The Anatomy of a Large-Scale Hypertextual Web Search Engine, a basic idea and algorithm expalanation.
Brin and Page explain basic design of Google algorithm, how indexing works, etc. Unfortunelly, they did'nt share the source code :). Also the page provide link to the protoype of search engine, but it was seem broken.
At the time Google was born, there some prominent "commercial" search engine such Yahoo!, Altavista, Lycos. They make money from advertising on the search page. Google started its life as "academyc experimental", then get commercial success, event now as one of Internet-service-based giant company.