Search engines like google
How do they actually work?
My client has had several things done by me and now he asked me if i could code a php search engine system for him in exchange for some good $$$. I have never done anything like this, so how do these things work?
Can they be done in php? or are they made with another programming language?
Google has several hundreds of low powered computers continously searching the web and cacheing the pages. It is all then analysed for various factors like key words, link popularity, content, page hits, etc etc The complex mathematical formulas used is a Google secret much like Coca Cola's secret formula of their taste giving flavours.[The concentrate is made in one place and then shipped to various bottling plants across the globe]
When you make a search Google pulls out the results from analysed data of this cache. For this reason sometimes even if a website is down you can see it if you click on a cached link in Google.
Building a search engine is pretty complicated for even companies like Yahoo to have their own. Till recently they were actually powered by Google search engine. Now they are working on their own realsing the great potential to make money out of it. Or you can build a customised engine to make searches with a set group of websites. This is especially useful for a closed group of users like a specific country search only or a search of any category of sites like dating, sports, jobs etc.
Then there are meta search engines which can give out results from other search engines. There is also search engines which give out clustered results. See vivisimo.com for example.
Another important tool is for search engine analysis. See copernic.com's Copernic Agent Pro which can meta search 1000+ search engines and analyse and filter them, search, save the results and even check the links for breaks.