RSS enclosure

RSS enclosures are a way of attaching multimedia content to RSS feeds with the purpose of allowing that content to be prefetched.^[1] Enclosures provide the URL of a file associated with an entry, such as an MP3 file to a music recommendation or a photo to a diary entry. Unlike e-mail attachments, enclosures are merely hyperlinks to files. The actual file data is not embedded into the feed (unless a data URL is used). Support and implementation among aggregators varies: if the software understands the specified file format, it may automatically download and display the content, otherwise provide a link to it or silently ignore it.

The addition of enclosures to RSS, as first implemented by Dave Winer in late 2000 [1], was an important prerequisite for the emergence of podcasting, perhaps the most common use of the feature as of 2012^[update] . In podcasts and related technologies enclosures are not merely attachments to entries, but provide the main content of a feed.

In RSS 2.0, the syntax for the <enclosure> tag, an optional child of the <item> element, is as follows:

<enclosureurl="http://example.com/file.mp3"length="123456789"type="audio/mpeg"/>

where the value of the url attribute is a URL of a file, length is its size in bytes, and type its mime type.

It is recommended that only one <enclosure> element is included per <item>.^[2]

The RSS <enclosure> has similarities to:

• the SMIL <prefetch> element,
• the HTML <link> element with rel="prefetch".[2]
• the HTTP Link header with rel="prefetch". (See RFC 2068 section 19.6.2.4.)
• the Atom <link> element with rel="enclosure"

• Broadcatching
• Internet television
• Podcast
• Photofeed
• Vlog

• The <enclosure> tag in the RSS 2.0 specification
• mod_enclosure - Enclosures in RSS 1.x
• Enclosure intended use case

• RSS
• Web syndication formats
• XML-based standards

• Articles with short description
• Short description matches Wikidata
• Articles needing additional references from September 2017
• All articles needing additional references
• Articles containing potentially dated statements from 2012
• All articles containing potentially dated statements