Codecs are applied to audio, video and image files to compress their size. The benefit is that the files don't use as much disk space when stored or as much network bandwidth when streamed. To open a compressed file, the same codec must be used to decompress the file.
Compression is the coding of data to reduce file size or tbe bit rate of a stream.
Lossy is a compression technique that decreases image, audio, or video quality in order to reduce the file size. So, the video codec is responsible for compressing the video frames during recording and for reconstructing the video frames during playback. Often, the makers of a codec will sacrifice image quality in order to achieve higher compression and smaller file sizes. The TSCC is optimized for screen capture so that the resulting files are small and highly compressed. The compression codec also affects the capture frame rate or speed of compression.