In Stand for the India. The website that follows the .in extension is meant to focus on users from the country India. There are two types of extensions, one showing the type of website (.org, .com) and the other showing the country it is in (.in Stand for India, .UK Stand for United Kingdom). Google.co.in means it has an Indian domain and is focused on users in India. Almost all countries have country specific domain names. This is known as a country code top-level domain (ccTLD), which is an Internet top-level domain typically used or reserved for a country. some of them are :-
There are 2 versions of any country code domain extension ".co.in" and simply ".in".