Base64
termAn encoding that represents arbitrary bytes using 64 printable characters, so binary data can travel through channels that only accept text.
It is not encryption and not compression: it makes data larger, by roughly a third, in exchange for surviving transports that would mangle raw bytes. The reason it is everywhere is historical - email was text-only, and everything built on that assumption inherited the need. Two practical notes: the URL-safe variant exists because plus and slash mean something in a URL, and seeing Base64 in a payload tells you nothing about whether the content is safe, which is why decoders belong in every analyst's toolkit rather than in their conclusions.
Also known as: base64url