Base64encodering

Base64encodering is a binary-to-text encoding scheme that represents binary data in an ASCII string format. In most contexts this technique is referred to as Base64 encoding rather than the coined term Base64encodering. It works by dividing input data into 24-bit blocks (three bytes) and mapping those bits to four 6-bit values, each encoded as an ASCII character. If the final block is fewer than three bytes, padding with equals signs (=) is added to complete the last four-character group.

The standard Base64 alphabet consists of the uppercase letters A–Z, the lowercase letters a–z, the digits 0–9, and the symbols + and /. A variant called Base64url uses - and _ instead of + and / to be URL-safe; there are additional MIME-friendly variants that insert line breaks every 76 characters.

Example: the ASCII string "Man" encodes to "TWFu". The strings "Ma" and "M" encode to "TWE=" and "TQ==", respectively, illustrating how padding works. Decoding reverses the process by converting each four-character block back to three bytes, removing any padding.

Uses include embedding binary data in text-based formats such as email MIME parts, data URLs, and JSON strings in which binary data cannot be represented directly. Base64 encoding increases data length by about one-third and is not designed for security; it provides no confidentiality and can be easily decoded by anyone with the encoded text.

Base64 encoding is standardized in RFC 4648 and its URL-safe variant; earlier MIME specifications (RFC 2045/2046) defined related encodings. It remains widely used because it provides a simple, portable way to transmit binary data in systems that handle text.