The purpose of switch is to switch the data from one device to another. By default, switch is a layer 2 device. Cisco switches are known as Catalyst. A switch, which works on more than one layers of OSI model, is known as Multilayer switch.
Cisco Switch Series:
CAT 1900 and CAT 2900 are the series, which works on layer 2.
CAT 3500, CAT 4000, CAT 5500 and CAT 6500 series switches are multilayer switches.
You can check the model of a switch by show version command on privillage mode.
Interfaces on a switch which connects one device to another for communication, are known as ports. By default, ports of a switch are of layer 2 ports. Layer 2 ports are known as switch ports. You can convert them to layer 3 ports by configuration. Command for converting layer 2 switch port to layer 3 is (no switchport). There are two types of ports on switches and routers. One is configuration and the other is communication. Steps performed on a device, which enable the device for communication, are known as configuration. If configuration is not done on a device, the device cannot use for communication.
Configuration ports: Console port and Auxiliry ports are configuration ports.
Ethernet 10 Mbps
Fast Ethernet 100 Mbps
Gigabit Ethernet 1000 Mbps
10 Giga 10 * 1000 Mbps
Switch is faster than router because of speed of its ports.