A keypad is a device that consists of buttons or keys arranged in a grid pattern, typically with letters and numbers. It is used for entering data into electronic devices such as calculators, computers, mobile phones, and other gadgets. The number of columns varies depending on the design, but most keypads have either 10 or 12 rows. Each button represents a specific character or function, and pressing multiple buttons together can perform different operations. Keypads are commonly used for authentication purposes such as entering passwords or accessing secure areas.