What does it mean to "Index a page"?

Question

For example in the sentence: "This tells Google how to index the page" what does Index the page mean in the grand scheme of things. Why would a page have an 'index.' What is it useful for?

Answer 1

Google servers are constantly visiting pages on the Internet (crawling) and reading their contents. Based on the contents Google builds an internal index, which is basically a data structure mapping from keywords to pages containing them (very simplified). Also when the crawler discovers hyperlinks, it will follow them and repeat the process on linked pages. This process happens all the time on thousands of servers.

In general, the term indexing means analyzing large amounts of data and building some sort of index to access the data in more efficient way based on some search criteria. Compare it with database indexes.

Answer 2

i guess you are asking the question of whats the need for indexing with google? Here it is why? After creating a website that is very beautiful and have all good features. But as i guess You would have know that web is all about connecting the Webpages! And you have created a site, in which you can only look at it. If the world want to know about your site, the next step will be hosting! After that obviously you have to do index your webpage to any search engine, say for example google. Now your site will be indexed according to the google bot, i cant explain how bot works! And if the person searching your site name in any engine then that engine with the help of indexing can retrive your page as the result :) This is how you connect to the WEB!