When you make a blog entry, that entry appears on the front page of your blog. You can typically choose how many blog entries will appear on your front page, and as you continue to add entries, older entries fall off of the front page they arent deleted, they just no longer appear on the front page. But what happens to them, and how can you or your readers access them again?
This is where permalinks come in. A permalink is a website URL for a blog entry. It is a permanent URL, where that blog entry will reside until you delete the post, or delete your entire blog. You can return to a specific entry by locating it in your blog archives. Blogger was the first blogging community to use permalinks in 2000.
You need permanent links for a variety of reasons. First, if someone else wants to quote something in one of your blog entries and give you credit for it, as they should, they will need the permalink to quote the source. This permalink will also be used for Trackback purposes. By using the permalink, the link never becomes outdated or broken again, unless you delete the blog entry or delete your entire blog. The link remains the same even if you later edit the entry.
This all sounds like the technical side of blogging, but you need to understand what permalinks are, and how they are used because you will be using them as well. When you visit another persons blog, and you want to quote an entry or provide a Trackback, you will need the permalink for that entry. Often, you will find entries on the front page of a persons blog, as opposed to finding them in the archives, which you wish to quote. The link to the front page of the persons blog is not the link that you want to use in your own blog post or Trackback.
Permalinks almost always include the month, day, and year in them, as well as the title of the entry. Also, even if you later change the title of an entry, the permalink will continue to have the old title otherwise, it wouldnt be a permalink. Permalinks may also contain the category name if you have assigned an entry to a specific category that you have set up for your blog.
To sum it up, permalinks are as important to the blogosphere as pinging and Trackbacks are. Make sure that you learn how to locate and properly use permalinks so that you can accurately link to other peoples blog entries. You may even find that you often need to link to your own blog entries. For instance, if you are participating in a forum, and want to direct someone to an entry that you have made that pertains to a forum topic, you will need the permalink for that entry.