A widely used email encoding that represents all bytes as printable 7-bit ASCII characters using `=` as the escape character, while also limiting line length to 76.
From https://en.wikipedia.org/wiki/Quoted-printable (slightly edited):
Quoted-Printable, or QP encoding, is an encoding using printable ASCII characters [...] to transmit 8-bit data over a 7-bit data path or, generally, over a medium which is not 8-bit clean.
It is defined as a MIME content transfer encoding for use in e-mail. QP works by using the equals sign
=
as an escape character.It also limits line length to 76, as some software has limits on line length.
Quoted-Printable is efficient and reasonably human-readable only for input text with mostly 7-bit ASCII characters, such as English text.