Encoding is the process of converting data from one form to another. While "encoding" can be used as a verb, it is often used as a noun, and refers to a specific type of encoded data. There are several types of encoding, including image encoding, audio and video encoding, and character encoding.
Media files are often encoded to save disk space. By encoding digital audio, video, and image files, they can be saved in a more efficient, compressed format. Encoded media files are typically similar in quality to their original uncompressed counterparts, but have much smaller file sizes. For example, a WAVE (.WAV) audio file that is converted to an MP3 (.MP3) file may be 1/10 the size of the original WAVE file. Similarly, an MPEG (.MPG) compressed video file may only require a fraction of the disk space as the original digital video (.DV) file.
Character encoding is another type of encoding that encodes characters as bytes. Since computers only recognize binary data, text must be represented in a binary form. This is accomplished by converting each character (which includes letters, numbers, symbols, and spaces) into a binary code. Common types of text encoding include ASCII and Unicode.
Whenever data is encoded, it can only be read by a program that supports the correct type of encoding. For audio and video files, this is often accomplished by a codec, which decodes the data in real-time. Most text editors support multiple types of text encoding, so it is rare to find a text file that will not open in a standard text editor. However, if a text editor does not support the encoding used in a text document, some or all of the characters may appear as strange symbols rather than the intended text.