Network is a group of devices linked together to share data. A network breaks barriers of distance, cost and time, and is cost-effective. Networks transmit different types of data like text and audio. Networks use transmission media like guided media which uses cabling, and unguided media which doesn't use cabling. Common transmission media include twisted pair cable, coaxial cable, optical fiber, infrared, Bluetooth, Wi-Fi, microwave, radio waves, and satellites. Networks can be local area networks spanning a small area like an office, metropolitan area networks spanning a city, or wide area networks spanning countries. The Internet is a worldwide network that allows uses like accessing information and using communication tools.