usually,
two or more computers
a hub or switch
cables to put it al together.
however there are also routers that are used on larger networks
How do you mean 'how networks are used'
simply networks are used to connect computers together.
situation 1 - home network connects your two + home machines together
2 - small business network - connects many more machines and possibly has networked printers attached
3 - latrger buisiness network conects many many machines accross different domain
4 - wide area network - (ex: the internet) connects many many machines over a large distance, backbone are used because of their suitability for carrying signals over large distances and carrying large amounts of data (the media has a large bandwidth) fibreoptic cable is practically limitless on the run lengths that can be achieved cat 5 cable is limited to something like 295 feet (look this up on google or something)
5 - Corperate networks - cnnects many machines accross multiple domains in multiple locations making use of the internet to provide site to site connections between smaller local are networks
6 - Virtual private networks - connect computers togehter over the internet using secure encypted tunnels to make sure the data is kept private and secure
7 - (i've actually run out of ideas!)
or did 'list eexamples of how networks are used' infere something about network topology?
in which case
1 - bus networks eg: BNC 75ohm coxaial cables conecting machine to machine the end machines being terminated with 75ohn terminators to prevent bouncing.
2 ring network, where conputers are arranged in a daisy chain fashion, eg computer 1 connects to computer 2 which connects to computer 3 which connects to computer 4 which connects to computer 1, each network card has an input and output port
3 - start networks like cat 5 neworks, work out from a central hub with terminal connecting to the hub, when drawon out can look like a wheel with the terminals being the spokes that fan out away from the hub.
I can't really think of any more topologies
or was it standards of interface?
in which case RS232 (large Dtype conectors)
BNC smaller round conectors
Cat5
Cat6
Cat7
Fibre wire
Serial (with crossover you can network 2 PC's via just the seral port)
USB (you can make that same kind of serial connection but with a USB cable (modified of course)
I hope one of those three answers will be of help to you.