A MIME type (also known as a media type or content type) is a label used to identify a type of data. It is used so software can know how to handle the data. It serves the same purpose on the Internet that file extensions do on Microsoft Windows³.

A MIME type consists of two parts: a type and a subtype, separated by a slash. For example, the MIME type for HTML documents is text/html, where text is the type and html is the subtype².

MIME types are defined and standardized by the Internet Assigned Numbers Authority (IANA), which maintains a list of all the official MIME types². Some examples of common MIME types are:

• text/plain: Plain text

• image/jpeg: JPEG images

• audio/mpeg: MP3 audio

• application/pdf: PDF documents

• application/json: JSON format

MIME types are case-insensitive, but conventionally written in lowercase². They can also have optional parameters to provide additional information, such as the character encoding of a text document. For example, text/plain;charset=UTF-8 indicates that the text is encoded in UTF-8².

MIME types are used in various contexts on the web, such as:

• In the Content-Type header of an HTTP response, to indicate the format of the response body².

• In the Accept header of an HTTP request, to indicate the formats that the client can understand².

• In the enctype attribute of an HTML form, to indicate how the form data should be encoded when submitted¹.

• In the type attribute of an HTML link or script element, to specify the style sheet or script language¹.

• In the plugins of browsers, to register themselves as handlers for certain MIME types³.