Creating a search engine in PHP

[pratik_learner]

How does one use PHP to create a search engine given it's great in-built string functions? Should the search-engine index only the meta-tags or the entire text body. Which is the most preferable backend application for storing the index file? Would XML be enough? All the XML tutorials I;ve been through just tell me that in XML you can define your own tags ; all the tags are case sensitive and should be properly nested . That's the end. How do I apply XML? SHould be asked in the XML section but just a question if you know.