A piece of network hardware that allows computers to talk to each other is called a network switch. You'll find several options when you look into purchasing a switch. These include unmanaged, managed, and smart managed. Within these categories there are also switches with additional features built in.
Switches perform the same function as hubs, in that you can form a network with one, but a switch is faster. Hubs used to be fairly popular several years ago because of their price. But, they have lost their popularity now that switch pricing has dropped dramatically, as well as the fact that they offer better performance.
The difference between switches and hubs lies with how information sent to them is processed. When a signal comes into a hub it will take that signal and send it to every computer on the network. Switches, on the other hand, will receive the signal and send it only to the computer the signal is intended to reach. As you can imagine network usage is cut down dramatically this way, especially with multiple computers all trying to send & receive data at the same time.
For an average home or small network an "unmanaged" switch is the most common type of switch. These types are referred to as plug and play (PNP) as you do not need to configure them for use. Simply plug them in and they are ready to work.
Large or special networks often use a "managed" switch. A managed switch has many settings administrators can change such as creating virtual LANs (VLAN's), setting the port speeds, and a host of other options. You need a web browser or a command line interface such as telnet or Secure Shell to access the switch settings.
A "smart managed" switch is a mix between an unmanaged switch and a managed switch. These switches are rapidly gaining popularity because they are as simple to use as unmanaged switches, but they allow you more control. You can determine such things as port speeds and VLANs, but they still don't have as many features as a managed switch does.
Two of the more popular features of switches are Jumbo Frames and Quality of Service. With Jumbo Frames a packet of data is allowed to be larger than the standard size. To use this feature both the switch and the Ethernet adapter need to support Jumbo Frames. The Quality of Service (QoS) feature prioritizes network traffic to allow data to be categorized so that the most important data is given priority.
For the diehard user (or if you want to be really organized) you can purchase a rack mount switch. Some rack mount switches are stackable meaning you can easily increase the number of computers on the network. But for a typical small network $ 10 can get you up and running.