Atom (web standard) facts for kids

For Atom feeds from Wikipedia, see Wikipedia:Syndication.

Quick facts for kids
Atom

Filename extension	.atom, .xml
Internet media type	application/atom+xml
Developed by	Internet Engineering Task Force
Initial release	RFC 4287 December 2005; 19 years ago (2005-12)
Type of format	Web syndication
Container for	Updates of a website and its related metadata (Web feed)
Extended from	XML
Open format?	Yes

User interface of a feed reader

Atom is a set of rules for how information on the internet can be shared and updated. It's like a special language that computers use to talk to each other about new content. There are two main parts:

The Atom Syndication Format is an XML language. It's used for something called "web feeds."
The Atom Publishing Protocol (often called AtomPub or APP) is a simple way to create and update web content using HTTP. HTTP is the system your web browser uses to talk to websites.

Web feeds let computer programs check for new updates on a website. Imagine your favorite blog or news site. Instead of visiting it every hour, a web feed can tell a program when new articles are posted.

To offer a web feed, a website owner uses special software. This software creates a list of recent articles in a format that computers can easily read. This list is the "feed." Then, other programs can download this feed. These programs might be websites that show content from many different feeds, or "feed reader" programs that let you subscribe to feeds and see their updates.

A feed contains "entries." These entries can be headlines, full articles, short summaries, or links to content. They also include extra information, like when the article was published.

Atom was created as a different option to RSS. Some people, like Ben Trott, felt that RSS had problems. They thought it wasn't improving enough and needed to stay compatible with older versions. A new design like Atom offered fresh ideas.

People who supported the new format formed a group called the IETF Atom Publishing Format and Protocol Workgroup. The Atom Syndication Format became an official standard in December 2005. The Atom Publishing Protocol became a standard in October 2007.

How is Atom Used?
Atom Compared to RSS 2.0
Why Isn't Atom Used More?
How Atom Was Developed
Example of an Atom 1.0 Feed
- Including in HTML
See also

How is Atom Used?

The world of blogging uses web feeds a lot. Bloggers share headlines, full articles, and even videos or audio files from their recent posts. Other websites can then show these "syndicated" headlines or summaries.

Today, people use Atom and other web feed formats for many things. This includes journalism, marketing, and even sharing bug reports for software. Basically, it's useful for anything that involves regular updates. Atom also offers a standard way to save an entire blog, or parts of it, as a backup. You can also use it to move your blog content to a different blogging system.

It's very common to find web feeds on big websites and smaller ones too. Some websites let you choose between RSS or Atom feeds. Others might only offer one. Many blog and wiki sites often provide their web feeds in the Atom format.

A feed reader or "aggregator" program helps you check feeds and see new articles. Some readers are standalone programs you install on your computer. Others are add-ons for web browsers.

Web-based feed readers don't need any software installation. They let you access your feeds from any computer with internet access. Some aggregators can even combine web feeds. For example, they might take all football-related news from several sports feeds and create one new football feed for you.

Atom Compared to RSS 2.0

When Atom first appeared, it was meant to be a competitor to RSS. People wanted a new format that would fix problems in RSS. They also wanted it to be managed by a proper standards organization.

Here are some ways Atom 1.0 is different from RSS 2.0:

Date Formats

RSS 2.0 uses a specific way to write dates and times. This is called RFC 822 format. It tells you when items in the feed were created or last updated. Atom, however, uses a different format called RFC 3339. This format is part of a bigger international standard for dates and times.

International Languages

RSS has a way to say what human language the whole feed is in. But it can't specify the language for individual articles or pieces of text. Atom, on the other hand, uses a standard feature called `xml:lang`. This lets it specify the language for every part of the content in the feed.

Atom also supports something called Internationalized Resource Identifiers. These allow links and unique IDs to include characters from different languages, not just the basic English alphabet.

Building Blocks

The parts of RSS are not usually designed to be reused in other computer languages. Atom's structure was made so that its parts can be used outside of an Atom feed document. For example, you might find `atom:link` elements being used inside RSS 2.0 feeds.

Why Isn't Atom Used More?

Even though Atom became an official standard and big companies like Google started using it, the older RSS formats are still very popular. Here are a few reasons why:

RSS 2.0 supports "enclosures." This feature directly led to the creation of podcasting. Many podcasting apps, like iTunes, do support Atom 1.0. However, RSS 2.0 is still the most common format for podcasts.
Many websites choose to publish their feeds in only one format. For example, CNN and The New York Times only offer their web feeds in RSS 2.0 format.
News articles about web feeds often use the term "RSS" to mean any type of web feed. This includes different versions of RSS and even the Atom format itself.

How Atom Was Developed

Background

Before Atom was created, the main way to share web content was through the RSS family of formats.

Some people felt that these RSS formats had big problems. But they couldn't make changes directly to RSS 2.0. This was because its official rules said it was frozen to keep it stable.

Early Work

In June 2003, a person named Sam Ruby started a wiki. A wiki is a website that anyone can edit. He wanted to discuss what makes a "well-formed log entry." This discussion became a starting point for many people. They quickly began using the wiki to talk about a new way to share content. They wanted to fix the problems of RSS. It also became clear that this new format could be a stronger replacement for blog editing tools.

The project aimed to create a web sharing format that was:

"100% vendor neutral," meaning no single company controlled it.
"implemented by everybody," so many programs would use it.
"freely extensible by anybody," meaning people could add new features.
"cleanly and thoroughly specified," meaning its rules were clear and complete.

Soon, a plan for the project was made. More than 150 people supported the effort. This included important figures from companies like Technorati, Six Apart, LiveJournal, Blogger, and Yahoo. Even Dave Winer, a key person behind RSS 2.0, gave some support.

After this, discussions became a bit messy because there was no clear way to make decisions. The project also didn't have a name. They used names like "Pie," "Echo," "Atom," and "Whatever" (PEAW) before finally choosing Atom. After releasing an early version called Atom 0.2 in July 2003, discussions moved off the wiki.

Atom 0.3 and Google's Use

The discussions then moved to a new mailing list. The next and final early version was Atom 0.3, released in December 2003. This version became widely used in tools for sharing content. Google especially added it to several of its services, like Blogger, Google News, and Gmail. Google's Data APIs, which are tools for developers, are based on Atom 1.0 and RSS 2.0.

Atom 1.0 and Official Standards

In 2004, people started talking about moving the project to an official standards group. They considered groups like the World Wide Web Consortium or the Internet Engineering Task Force (IETF). The group eventually chose the IETF. The Atompub working group was officially set up in June 2004. This finally gave the project a clear plan and process. The main focus at first was on the syndication format.

The Atom Syndication Format was released as an official standard by the IETF in December 2005. The Atom Publishing Protocol was released as an official standard in October 2007.

Example of an Atom 1.0 Feed

Here is an example of what an Atom feed document looks like in computer code:

<?xml version="1.0" encoding="utf-8"?>

<feed xmlns="http://www.w3.org/2005/Atom">

        <title>Example Feed</title>
        <subtitle>A subtitle.</subtitle>
        <link href="http://example.org/feed/" rel="self" />
        <link href="http://example.org/" />
        <id>urn:uuid:60a76c80-d399-11d9-b91C-0003939e0af6</id>
        <updated>2003-12-13T18:30:02Z</updated>
        
        
        <entry>
                <title>Atom-Powered Robots Run Amok</title>
                <link href="http://example.org/2003/12/13/atom03" />
                <link rel="alternate" type="text/html" href="http://example.org/2003/12/13/atom03.html"/>
                <link rel="edit" href="http://example.org/2003/12/13/atom03/edit"/>
                <id>urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a</id>
        <published>2003-11-09T17:23:02Z</published>
                <updated>2003-12-13T18:30:02Z</updated>
                <summary>Some text.</summary>
                <content type="xhtml">
                        <div xmlns="http://www.w3.org/1999/xhtml">
                                <p>This is the entry content.</p>
                        </div>
                </content>
                <author>
                        <name>John Doe</name>
                        <email>johndoe@example.com</email>
                </author>
        </entry>

</feed>

Including in HTML

To link to an Atom feed from an HTML webpage, you would put the following code in the `<head>` section of your HTML document:

<link href="atom.xml" type="application/atom+xml" rel="alternate" title="Sitewide Atom feed" />