Permalinks and Trackbacks

Some terminology has appeared that I generally ignore, even if I shouldn't. Two of these terms are permalinks and trackbacks.

The first concept, permalinks, is pretty easy to explain. Think of any website that changes content frequently, say, an online newspaper or a blog. You see a cool post and you want to provide a link. However, if you point to the main page, the link will go "bad" quickly, because the article won't stay on that page for very long.

Most blogs (and news websites) can put each article at a "unique" URL, usually based on the year and month the article was written plus the title of the article. For example, if I wrote an article on August 19, 2006 title "Why I Love Bananas", the URL might look like:

http://chaileaves.blogspot.com/2006/08/19/Why-I-Love-Bananas.html

This the "permanent" location of the article. I put "permanent" in quotes because it's not necessarily permanent. If Blogger were to go out of business, I would lose this link. If I were to delete my blog, then the link would disappear. If I were to revise that blog entry, then it's likely the date that it gets posted on may change to the new date of modification, and again, this permalink would get lost.

However, it's certainly more permanent than someone referring to the main webpage. When I need to refer to someone's blog entry, I find it on their page, then click on their permalink, which changes me to a webpage with only that one article in it, and cut and paste the URL, i.e., the permalink.

Trackbacks are a bit trickier. Suppose I read a great article in Joel On Software. I could add a comment to the article. But maybe I want to write it in my own blog. Suppose I want Joel to know that I wrote about his article. I could notify him that my blog entry (using my permalink URL) refers to his.

Ideally, I could to this without having to do any work. This would happen if, for example, Blogger, the blog service I'm using, and whoever is hosting Joel's blog can talk to each other. For example, suppose I post my article. The blog service (a program) runs a program and notices I refer to Joel's URL in my article. It automatically tries to contact joelonsoftware.com and inform it that there's an article written that refers to the permalink, which then updates his article to have a link to mine's.

This might be fine except for a few annoyances. First, maybe I don't want Joel to know that I've referred to his article, or at least, not so that it adds a link to the end of his article that others can access. Maybe I've said something negative or stupid and even though I posted it, it's not what I want everyone to remember me by. Or perhaps he doesn't want to get spammed by trackbacks.

To be honest, I'm not sure how all the communication works to make it happen. It may be far more manual than that (I'm looking at Blogger's mechanism. They apparently have something called backlinks which is the same thing, and rely on blogs that are indexed by Google's Blog Search to attach appropriate backlinks to your blog).

Yeah, that was tougher to explain that I wanted, which is why most people probably don't care about it and don't understand it.