If you are appearing in a Google recruitment test or campus placement test, then you need to know about Google. I will tell you what Google does and its various businesses.

Google derives most of its revenue and brand equity from being a big search engines which finds results from billions of web pages on the internet using its advanced algorithm.
Google is the largest and most popular search engine. It makes money by listing sponsored advertisements above search results and on the right hand side bar.
Google also has a program by which it shows ads on website publishers’ sites and in turn pays them. The program is called google adsense.

Google has other significant services like Orkut – a popular social networking site, Youtube – the world’s largest video sharing website and community, Gmail – a largely popular web based free email service and other offerings.
Gmail is also currently collaborating with businesses for email solutions. It recently collaborated with Australian education authorities for running their email systems.

Google has a large team of people who manually review sites, give ratings and descriptions on certain parameters. It helps Google eliminate spam and improve its search results.

Google has other services like Documents including Notebooks, Spreadsheets, etc. It also has a google gadgets feature, Google earth, Google maps and listings, etc. It also runs Google groups – the largest discussion g

Google has also recently launched its free wiki like service called google sites. Google tries hard to stay innovative and lead the online industry. Most services are given free to customers.
THere are other specific things which google engages in but i have mentioned most of them here.

Other Google companies or those recently acquired by Google are:
Feedburner – Viewing website feeds
Youtube.com – Video sharing website – the largest and most popular in the world
Blogger – Blogspot.com – Users can build their free blogs
Doubleclick.com – Ad Serving technology
Mozilla Foundation – Firefox browser and more

Google is also developing its mobile operating system called Android based on which a new product is just about to be launched soon by HTC. Google is one of the most preferred employers and is a great workplace!