In message , Oppie writes
It's a way to direct the nasty at localhost,
add lines like;
127.0.0.1 adhost.nasty.spywareto %systemroot%\\system32\\drivers\\etc\\hosts
Any program that tries to access adhost.nasty.spyware will get directed to localhost but it takes time for the nasty to time out so it can slow your machine down. Good way to stop spyware if you can find a list of hosts.
You can also use it to give your network 'friendly' names instead of IP addresses but it's not easy to manage if your network has more than, say, five machines as it has to be the same on each machine.