Internet has turned out to be one of the most powerful medium of information exchange available today. This virtual world is composed of millions of websites which act as the source of information on all aspects of human life. The tons of data you see spread across the web needs to be to stored some where.
Computer specialists save this information on computer hard disks and then link it to internet so that it can be accessed from any location in the world. This "computer" is usually referred to as a "web server" and data stored on it is known as being "hosted" hence the term Web Hosting.
These web servers are placed in special locations called the "data centers". Many technological companies own and operate data centers and a few let other commercial Web Hosting companies use their facility by charging them a co-location fee.
Technology has progressed a lot which has resulted in the creation of extremely powerful computers that can handle a lot more data per second than they would have done 10 years ago. Web servers are specially designed computers that have the ability to run 24 hours a day non stop for years at a time as long as the necessary cooling environment is provided to it. Both Intel and AMD produce highly sophisticated server chips aimed at heavy processing of data.