A Made IT project
For a good understanding of switches you should first understand bridges. A switch is nothing more than a fast mult-port bridge.
The difference between a bridge and a switch is that a bridge copies a packet from the network, analyzes it and forwards it to the right port and will then look at other ports to see if there is another packet. This whole process may take about 1500 bytes (an ethernet frame) or roughly 1200 µs.
A switch looks at the first part of a frame (the destination address) and then sends it through to another port, meanwhile it can look at the other ports if there is more to do in which the occupied ports have no part. This can speed up the switching process to about 40 µs.
A switch can be seen as a matrix bridge, which makes parallel paths possible.
A note concerning switches: if you only have one server and all LAN traffic goes to and from that server, a switch will NOT solve your problem. All data still needs to go to that server over that single ethernet segment.