The Internet.

Welcome to the Internet. At this moment in time, who could possibly know what will be used in 50 years? We certainly don't.
The Internet is a globally-used WAN... which can be accessed almost instantaneously, anywhere in the world.

There are, however, many different ways to access the Internet. Obviously there is the need for a computer, which must be used with other pieces of hardware to gain access. A table can be found here with details of speeds available to many Internet users.

For a more detailed look at how the Internet is used please have a look at ICT at School and Leisure -> Internet.