I/O stands for "Input/Output," which refers to the communication between a computer and the outside world. Input is the data or commands sent to the computer, such as keyboard strokes or mouse clicks, while output is the information the computer sends back, like displaying text on a screen or printing a document. I/O operations are essential for a computer's functionality, allowing it to interact with users and other devices. Common I/O devices include keyboards, mice, monitors, and printers. Efficient I/O management is crucial for system performance, ensuring smooth data transfer and processing.