The "Caps Lock" key is a toggle key found on computer keyboards. When activated, it causes all letters typed to appear in uppercase without needing to hold down the "Shift" key. This feature is useful for typing titles, headings, or any text that requires emphasis. Most keyboards have the "Caps Lock" key located on the left side, near the "A" key. It is often indicated by a light that turns on when the function is active. Users can easily turn it off by pressing the key again, returning to normal typing mode with lowercase letters.