A virtual location! When logged on to the internet each computer has a unique IP address, that is the internet protocol address. This simply means to identify and locate as to where on the internet protocol is your pc located.
Mostly as and when a computer connects to the internet a dynamic random IP address is generated and dedicated to the PC for as long as it does not get disconnected. The next time the same PC is connected, it would have a different IP address, this holds true in case of both broadband and dial up connections.
When internet was in its nascent stage each computer had a fixed exclusive IP address. Which was in a patter of digitis however dynamic IP's have been fairly popular in the present scenario?
However on demand there are few providers who offer static IP`s to users. Static IP's are like a constant IP address of a computer on the network and is ideal for people using private networks (VPN) for they can be easily located by other members on the network.
However some broadbands are run on private networks mostly for the privacy and safety business communication. Often people also run a server for friends to access for playing games and web serving etc. In such cases they prefer static IP addresses for there might be a domain name linked to their IP address so if the IP address is not fixed it would be tough to locate the server!.
Hence it widely depends on your preference and perception of Internet to choose a static or a dynamic IP address.