A codec is a device or software that compresses and decompresses digital media files, such as audio and video. The term is a combination of "coder" and "decoder." Codecs are essential for reducing file sizes, making it easier to store and transmit media over the internet. Common examples include MP3 for audio and H.264 for video. Different codecs use various algorithms to achieve compression, which can affect the quality of the media. Some codecs are designed for specific purposes, like streaming or broadcasting, while others prioritize high fidelity. Understanding codecs is important for anyone working with digital media.