MIMEenkoodauksessa

MIME (Multipurpose Internet Mail Extensions) is a set of specifications that extend the original Internet email format to support text messages with characters in character sets other than ASCII, as well as binary attachments. It allows for the transmission of non-textual data such as images, audio, and video files over email. MIME defines several header fields that specify the content type and encoding of the message body, enabling email clients to correctly interpret and display or process the content.

The core of MIME encoding involves representing binary data in a format that can be transmitted through text-based protocols like SMTP. The most common MIME encoding is Base64, which converts arbitrary binary data into a sequence of printable ASCII characters. Other encoding schemes, such as quoted-printable, are used for text that contains non-ASCII characters, preserving readability while allowing for international characters.

When an email contains attachments or non-ASCII text, MIME headers are added to the message. Key MIME headers include Content-Type, which specifies the media type (e.g., text/plain, image/jpeg) and any character set, and Content-Transfer-Encoding, which indicates how the body content has been encoded (e.g., base64, quoted-printable). These headers are crucial for the receiving email client to understand how to decode and present the message content to the user. Without MIME, the early internet would have been severely limited in its ability to share diverse types of information.