router

Yes and you need to be more specific.

There are many different kinds of networks you can setup so your needs should be specified for an accurate answer.

Like do you just need two computers hardwired to an internet connection or do you have a massive compound with thousands of computers covering hundreds of square miles with the need for wireless coverage?

If you are just talking about does it need to be an Airport Extreme? No, a DLink, Netgear or Linksys will work fine. Steer clear of cheapo brands (Airlink) since they usually have limited customization in the web interfaces.