A network interface is a point of connection between a computer or device and a network. It allows devices to communicate with each other over a network, such as the internet or a local area network (LAN). Network interfaces can be physical, like an Ethernet port, or virtual, like a software-based interface used in virtual machines. Each network interface has a unique identifier called a Media Access Control (MAC) address, which helps in distinguishing devices on the network. Network interfaces can support various protocols, such as TCP/IP, enabling data transmission and reception across different types of networks.