A video codec is a technology used to compress and decompress digital video files. It allows for efficient storage and transmission of video data by reducing file size while maintaining quality. Common video codecs include H.264, H.265, and VP9, each with different levels of compression and compatibility. When a video is recorded, it is often too large to store or share easily. A codec helps by encoding the video into a smaller format. When you play the video, the codec decodes it back to a viewable format. This process is essential for streaming services like YouTube and Netflix.