Base64 encoding is a process of converting binary data to an ASCII string format by converting that binary data to a 6-bit character representation. The Base64 encoding method is used when binary data, such as images or video, is sent over systems that are designed to send data in a plain text (ASCII) format.

The need for Base64 encoding arises from the problems encountered when sending media in a raw binary format to text-based systems.

Because text-based systems (such as e-mail) interpret binary data as a wide variety of characters, including special command characters, much of the binary data sent to transmission media is misinterpreted by these systems and is lost or corrupted during the transmission process.

One method of encoding this kind of binary data in a way that avoids such transmission problems is to transmit it as plain ASCII text in Base64 encoded format. This is one of the techniques used by the MIME standard to transmit data other than plain text.