A CPU socket is a physical interface on a computer's motherboard that allows a central processing unit (CPU) to be installed and connected to the system. It provides the necessary electrical connections and mechanical support for the CPU, enabling it to communicate with other components like memory and storage. Different types of CPU sockets exist, each designed for specific CPU models and architectures. For example, Intel and AMD use different socket types, which means a CPU from one manufacturer cannot fit into a socket designed for the other. Proper socket compatibility is crucial for building or upgrading a computer.