Editing Base64 (section)

{{Short description|Group of binary-to-text encoding schemes}}
In [[computer programming]], '''Base64''' is a group of [[binary-to-text encoding]] schemes that transforms [[binary data]] into a sequence of [[Graphic character|printable]] characters, limited to a set of 64 unique characters.  More specifically, the source binary data is taken 6 bits at a time, then this group of 6 bits is mapped to one of 64 unique characters.

As with all binary-to-text encoding schemes, Base64 is designed to carry data stored in binary formats across channels that only reliably support text content. Base64 is particularly prevalent on the [[World Wide Web]]<ref>{{cite web |title= Base64 encoding and decoding – Web APIs |url= https://developer.mozilla.org/en-US/docs/Web/API/WindowBase64/Base64_encoding_and_decoding |publisher= MDN Web Docs |archive-url= https://web.archive.org/web/20141111151440/https://developer.mozilla.org/en-US/docs/Web/API/WindowBase64/Base64_encoding_and_decoding |archive-date= 2014-11-11 |url-status=live}}</ref> where one of its uses is the ability to embed [[image files]] or other binary assets inside textual assets such as [[HTML]] and [[CSS]] files.<ref>{{cite web |title= When to base64 encode images (and when not to) |date= 28 August 2011 |url=https://www.davidbcalhoun.com/2011/when-to-base64-encode-images-and-when-not-to/ |archive-url= https://web.archive.org/web/20230829143759/https://www.davidbcalhoun.com/2011/when-to-base64-encode-images-and-when-not-to/ |archive-date=2023-08-29 |url-status=live}}</ref>

Base64 is also widely used for sending [[e-mail]] attachments, because [[Simple Mail Transfer Protocol|SMTP]]&nbsp;– in its original form&nbsp;– was designed to transport [[7-bit ASCII]] characters only. Encoding an attachment as Base64 before sending, and then decoding when received, assures older SMTP servers will not interfere with the attachment. 

Base64 encoding causes an overhead of 33–37% relative to the size of the original binary data (33% by the encoding itself; up to 4% more by the inserted line breaks).

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