What algorithm does google use to make Chrome browser's address bar to act as a default search bar for many websites?

Question

I am wondering what algorithm does google use to make chrome browser\'s address bar to act as a default search bar for many websites like SO, Quroa etc. but not for facebook, me

Answer 1

This feature is powered by what is known as OpenSearch. It allows you to specify how queries are supposed to be formed when searching a website. You can read the documentation here: http://www.opensearch.org/Home

For example, StackOverflow has the following in their HTML source code:

If you then open the file /opensearch.xml you can see the following:

  Stack Overflow
  Search Stack Overflow: Q&A for professional and enthusiast programmers
  UTF-8
  http://sstatic.net/stackoverflow/img/favicon.ico
  

The most important part is the line that specifies the search term string in line 7.