How do Web search engines work?

I had posted an article with the title shown above in this blog by mistake. It really belongs to another blog of mine named
https://hindimestem.blogspot.com/2017/09/blog-post.html
That blog carries Hindi and English versions of a series of articles on Web Search. Some are already there and more are getting ready. I have moved the article wrongly posted here.

Srinivasan Ramani