A network adapter is a hardware component that allows a computer or device to connect to a network, enabling communication with other devices. It can be wired, using an Ethernet cable, or wireless, using Wi-Fi technology. Network adapters convert data into a format suitable for transmission over the network and vice versa. These adapters can be built into the device, like in most laptops, or can be added externally, such as USB network adapters. They play a crucial role in connecting devices to the internet or local networks, facilitating activities like browsing, streaming, and file sharing.