Base64 encoding was originally conceived more than 30 years ago (named in 1992). Back then, the Simple Mail Transfer Protocol (SMTP) forced developers to find a way to encode e-mail attachments in ASCII characters so SMTP servers wouldn’t interfere with them.

All these years later, Base64 encoding is still widely used for the same purpose: to replace binary data in systems where only ASCII characters are accepted. E-mail file attachments remain the most common example of where we use Base64 encoding, but it’s not the only use case. Whether we’re stashing images or other documents in HTML, CSS, or JavaScript, or including them in JSON objects (e.g., as a payload to certain API endpoints), Base64 simply offers a convenient, accessible solution when our recipient systems say “no” to binary.