A programmable logic controller (PLC) is a digital computer used for automation of industrial processes. It monitors inputs from various sensors and devices, processes the information, and controls outputs to machinery or systems based on pre-defined logic. PLCs are designed to withstand harsh environments, making them ideal for manufacturing and production lines. PLCs can be programmed using specialized software, allowing engineers to create custom control sequences. They are widely used in applications such as assembly lines, robotics, and traffic control systems. Their flexibility and reliability make them essential tools in modern industrial automation.