Mime format what is it

Jennifer Kyrnin. Freelance Contributor. Updated on June 12, Michael Barton Heine Jr. Lifewire Technology Review Board Member.

Article reviewed on Sep 28, Tweet Share Email. How do browsers deal with unknown MIME data types? Was this page helpful? Thanks for letting us know! Email Address Sign up There was an error. Please try again. You're in! Thanks for signing up. There was an error. Tell us why! More from Lifewire. Your Privacy Rights. I have tried to look into it and know that it is Multipurpose Internet Mail Extensions MIME but no suitable explanation of how it relates to browser plug-ins, as in what I need to know about it for building plug-ins, is provided, please explain in clear and simple words.

What is it? Why do plug-ins have a MIME type? A MIME 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 Windows.

You'll most commonly find them in the headers of HTTP messages to describe the content that an HTTP server is responding with or the formatting of the data that is being POSTed in a request and in email headers to describe the message format and attachments. MIME types form a standard way of classifying file types on the Internet.

Internet programs such as Web servers and browsers all have a list of MIME types, so that they can transfer files of the same type in the same way, no matter what operating system they are working in. A MIME type has two parts: a type and a subtype. Although there is a complete list of MIME types, it does not list the extensions associated with the files, nor a description of the file type.

This means that if you want to find the MIME type for a certain kind of file, it can be difficult. Sometimes you have to look through the list and make a guess as to the MIME type of the file you are concerned with. It's a way of identifying files on the Internet according to their nature and format.

Nowadays, this standard is used in a lot of other protocols, hence the new naming convention "Internet Media Type". A MIME type is a string identifier composed of two parts: a type and a subtype. The x- prefix of a MIME subtype simply means that it's non-standard. The vnd prefix means that the MIME value is vendor specific. Imagine that you wrote a letter to your pen pal but that you wrote it in different languages each time.

For example, you might have chosen to write your first letter in Tamil, and the second in German etc. So then, in order to highlight the language you are writing in, you simple annotate the language e. How would your friend know or be able to read or distinguish between the different language types you are specifying at the top of your letter?

That's easy: you agree upon this beforehand. Because there are different types of data formats which need to be sent over the internet, specifying the data type up front would allow the corresponding client to properly interpret and render the data accordingly to the user. For example, a PDF format is very different from a picture format - which is also different from a sound format - both serve very different purposes and accordingly are written different prior to being sent over the internet.

I couldn't possibly explain it better than Wikipedia does in Media type :. This enables the browser to display or output files that are not in HTML format. In other words, it helps the browser or content consumer, because it may not just be a browser determine what content they are about to consume; this means a browser may be able to make a decision on the correct plugin to use to display content, or a media player may be able to load up the correct codec or plugin.

All HTML content should be served with this type. No other values are considered valid, and using any of those may result in scripts that do not load or run. For historical reasons, the MIME Sniffing Standard the definition of how browsers should interpret media types and figure out what to do with content that doesn't have a valid one allows JavaScript to be served using any MIME type that essentially matches any of the following:.

It's the only MIME type guaranteed to work now and into the future. This is not valid, and in most cases will result in a script not being loaded. Files whose MIME type is image contain image data. The subtype specifies which specific image file format the data represents.

The following image types are used commonly enough to be considered safe for use on web pages:. The Image file type and format guide provides information and recommendations about when to use the different image formats.

Our media container formats guide provides a list of the file types that are commonly supported by web browsers, including information about what their special use cases may be, any drawbacks they have, and compatibility information, along with other details.

The audio codec and video codec guides list the various codecs that web browsers often support, providing compatibility details along with technical information such as how many audio channels they support, what sort of compression is used, and what bit rates and so forth they're useful at. The codecs used by WebRTC guide expands upon this by specifically covering the codecs supported by the major web browsers, so you can choose the codecs that best cover the range of browsers you wish to support.

As for MIME types of audio or video files, they typically specify the container format file type. The optional codecs parameter can be added to the MIME type to further specify which codecs to use and what options were used to encode the media, such as codec profile, level, or other such information. The most commonly used MIME types used for web content are listed below. This isn't a complete list of all the types that may be available, however.

See the media container formats guide for that. As a multipart document format, it consists of different parts, delimited by a boundary a string starting with a double dash When the Partial Content status code is sent, this MIME type indicates that the document is composed of several parts, one for each of the requested ranges.

Like other multipart types, the Content-Type uses a boundary to separate the pieces. Each piece has a Content-Type header with its actual type and a Content-Range of the range it represents. For security reasons, most browsers do not allow setting a custom default action for such resources, forcing the user to save it to disk to use it. Each browser performs MIME sniffing differently and under different circumstances.

There are security concerns as some MIME types represent executable content. Discrete types The discrete types currently registered with the IANA are: application Any kind of binary data that doesn't fall explicitly into one of the other types; either data that will be executed or interpreted in some way or binary data that requires a specific application or category of application to use. Registration at IANA text Text-only data including any human-readable content, source code, or textual data such as comma-separated value CSV formatted data.

Multipart types Multipart types indicate a category of document broken into pieces, often with different MIME types; they can also be used — especially in email scenarios — to represent multiple, separate files which are all part of the same transaction.