A video codec is a technology used to compress and decompress digital video files. It reduces the file size for easier storage and transmission while maintaining quality. Common video codecs include H.264, H.265, and VP9, each with different levels of efficiency and compatibility. When a video is recorded, it is often too large to share easily. A codec helps by encoding the video data 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 to deliver content efficiently.