I've spent a lot of time trying to explain what Web 2.0 means, both in my columns and in conversations with people. Normally, I start with what I consider to be the easiest part—saying something like, "A classic example of a Web 2.0 application is a blog." This is typically followed by the person nodding his or her head and saying, "Oh, I know what a blog is."

But the funny thing is, when I start to dig deeper, it often turns out that the people I am talking to have only a very basic understanding of what a blog is. Many people can't even really tell the difference between a blog and a regular Web page.

If I ask a person to describe to me what he or she thinks a blog is, the person will say something like, "Well, it's a Web site, with a bunch of little stories rather than long ones, and they go down in a list based on when they were posted."

Now, if this was the only misconception among laypeople—or, those who don't really need to know all of the ins and outs of blogs—that would be one thing. However, I'm also starting to see lots of vendors claiming that their enterprise products have integrated blogging capabilities. But when I look at these products, they often come up very short in several areas crucial to a real blog.

So, as a service to all of you who want to implement blogs but who aren't totally clear on what the capabilities, features and characteristics of a real blogging platform are, here is my take on what makes a blog a blog.

First, let's start with the obvious stuff. A blog needs to be easy to publish to, preferably with a simple-to-use browser interface for posting stories, creating categories and adding content. Many popular blogging platforms, in fact, make it possible to use offline client tools so that you can publish right from your desktop.

Second, a good blog should make it easy for readers to comment on stories and read comments from other readers. Anything that makes readers leave a post to comment is basically destroying the interactive blogging dynamic.

Finally, and most crucially, a blog needs integrated feeds, based on RSS and Atom. Blog users shouldn't have to do anything to make it possible for readers to subscribe to the blog feed—the process should be totally automatic. It also should be possible to subscribe to feeds of blog content in multiple ways, such as subscribing to specific categories or posts by a specific author.

Every so-called corporate blogging product I've seen has these capabilities—and, for many people, that's sufficient. But if your blog has only these capabilities, it's still not a blog. It's just a Web site with comments and enabled feeds.

That's because the core things that make a blog a blog are how it interacts with other blogs and how it promotes itself to search engines, blog aggregators and other sites.

A blog must have support for trackbacks, which make it possible for one blog to interactively comment and link to a post on another blog. This is a key feature that often I'm surprised to find missing in many products that claim to be blogging platforms.

The blog application also should include what is commonly called a ping feature. Different from the standard TCP/IP type of ping, the blogging ping feature enables a blog to notify aggregators and other Web sites whenever new content is added. While this is less vital in an internal corporate blog, any blog that wants to be seen by the outside world should include this capability.

If you want your blog to link to other blogs and you want those blogs to know that you are linking to them (and hopefully have them link back to you), then your blog application also should include blogroll features. Rather than being just a list of links, blogroll features are designed to let other blogs know that they have been added.

There are lots of other things that a good blog site should have—including many administrative, security and anti-spam features—but the criteria I have provided above is a good start to weeding out the real blogging tools from the wannabe Web site pages.

Labs Director Jim Rapoza can be reached at jim_rapoza@ziffdavis.com.