Almost every significant web-project is usually located in data-center, wherever this data-center is located - locally, in provider's place or in the cloud.
Data-centers are centralized locations where computers and network equipment is stored. These computers and equipment are used to store, process and distribute data. The size of data-centers may vary greatly - from several servers in your office to great space with thousands of very powerful servers that work without interruption and require steady power supply and Internet connection.
What computers are used in data-center?
The biggest difference of usual office computer from server is the productivity. Servers usually have more RAM, more storage space, have more powerful processors. Servers are not usually connected to monitors or other peripherals - the connection to them is made remotely.
How a data-center works?
Data-center is usually connected to one or several providers and multiple routers that choose the best route for receiving and sending information.
What is the difficulty in data-center management?
Data-centers are expected to work 24 hours a day and 7 days a week without any interruptions. Such problems as equipment failure, problems with electricity or network will prevent users from work and will require immediate interference. That's why there are always technicians present in data-center to deal with such problems immediately. Also backup policy is established.