A switch is similar to a hub, except that it registers the IP addresses of the computers plugged into it. When it receives a message, it only sends it to the intended recipient. Switches cut down on unnecessary traffic broadcasts and allow you to have an affordable high-performance network.
Switches are used to connect computers on the same network; they do not provide Internet access. You can still share your Internet connection through one of the computers on your network, however, as your network grows, you will see performance degrade. When one computer has to manage the Internet connection, it slows down network performance. If the main computer crashes, all of the other computers will lose their Internet connection. (You may also be able to plug your switch into your broadband modem, but only if you get multiple IP addresses from your provider. This usually costs more.) For increased performance and functionality, you need a router.
Switches are available as unmanaged, managed or with a combination of features usually referred to as smart or intelligent switches.
An unmanaged switch does not have a configuration utility or changable options. These switches are ideal for home and small office use.
A managed switch offers the ability to configure and manage individual ports as well as link speed and duplex settings. Features vary but may include Spanning Tree Protocol, Port Speed, VLANs, QoS, and more. Configuration access may be offered in a multitude of ways: serial console, command line, telnet, ssh, SNMP and now the more common web interface. Managed switches are ideal for medium to large networks. Managed switches can be very expensive, so many small to medium businesses prefer to use Smart Switches.
Smart (or intelligent) switches have capabilities that lie between unmanaged and managed switches and normally provide configuration of basic settings. They have some or all of the following: manageability, typically provided using a Web Interface which allows performance monitoring (port activity), the ability to configure network trunks (bandwidth control), and supports Port Mirroring. Quality of Service (QoS) which prioritizes traffic to support delay sensitive applications such as Voice over Internet Protocol (VoIP) and Streaming Video and enhanced security which offers support for Virtual LANs (VLAN).