A permalink … is a URL that points to a specific blog or forum entry after it has passed from the front page to the archives. Because a permalink remains unchanged indefinitely, it is less susceptible to [becoming a broken link]. Most modern weblogging and content-syndication software systems support such links. Other types of websites use the term permanent links, but the term permalink is most common within the blogosphere. Permalinks are often simply rendered so as to be human-readable.
Not only are they permanent, but they look good too
WordPress provides permalinks by default, but also allows you to choose simple, human-readable permanent URLs, referred to in WordPress as pretty permalinks. Not only are they permanent, but they also look nice.
The WordPress Admin explains it well:
By default WordPress uses web URLs which have question marks and lots of numbers in them; however, WordPress offers you the ability to create a custom URL structure for your permalinks and archives. This can improve the aesthetics, usability, and forward-compatibility of your links.
By default — if you set up a WordPress site and never change the permalink settings — your site’s URLs will look something like this:
The above is a permalink; but it isn’t a pretty permalink. That string at the end doesn’t mean anything to humans. Significantly, neither does it mean anything to Google.
A pretty permalink for the above page will look something like this:
It simply looks better and is more understandable to humans.
Choose a permalink structure and stick with it
So it’s important to choose a permalink structure, because if you don’t, the default ugly permalinks will be used.
And it’s best to choose a permalink structure when your website is new and stay with it, since the whole point of using permalinks in the first place is to have permanent URLs for your posts and pages.
Changing your permalink structure means that the links created by the old structure will now be broken links. People who follow the old links will see a 404 Page Not Found error message, and any SEO value the post had will be damaged. Obviously this is not what you want.
So during the process of setting up a new website, be sure to decide on and set up the permalink structure which seems best for your purposes, and don’t plan on changing it.
Making your Permalink settings
To set up permalinks for your site, log into the Admin and go to Settings > Permalinks.
This takes you to the Permalink Settings screen. Here, you’ll see a list of options.
Default produces the ugly permalinks discussed above. This is almost never the best choice. Numeric is not much better; I don’t know of any reason to use it.
That leaves 3 pre-set options, and the Custom option. So which is best for your website?
Post name is a good choice for most websites
The Post name setting will work well for most sites. Choosing Post name produces URLs which look like this:
They look neat and are understandable to both humans and search engines. The post name which is displayed is the post slug, a version of the actual page title stripped of punctuation, capital letters, and unimportant short words, with hyphens between the words. The actual post title is usually not usable as part of a valid URL, but the post slug is. WordPress will automatically create a post slug for it, which appears just below the title on the Edit Post screen.
You can edit the post slug however you like — on the Edit Post screen — as long as you follow the rules: no capital letters, no punctuation other than the hyphens between words. This way, you can fine-tune exactly what your post URL will be, as long as you choose a permalink structure which includes the %postname%.
Date-based permalinks are best for multiple-posts-per-day sites
For a website which has multiple posts per day, one of the date-based options is probably the best choice. Day and name and Month and name produce URLs like this:
For that type of website, having the date in your post URLs is only useful for staying organized, and for making sure each post can have a unique URL. Beyond that, I know of no reason to use date-based permalink structures. They add length to URLs and make them less friendly, and can even discourage people from clicking on a link to a post which is a bit old.
The Custom setting gives you lots of options
The permalink setting labelled Custom allows you to create a permalink structure by filling in its blank field with one or more of the structure tags provided.
Try this: select the radio button of any of the predefined permalink structures; notice that the Custom option reflects the same structure. This can be helpful to provide you with a starting point. You can then then add or subtract structure tags. A list of available structure tags is on the Using Permalinks page of the WordPress Codex.
Don’t put your domain name into the Custom field – only structure tags. Each structure tag needs a forward slash before and after it, with just one slash in between tags.
A custom setting of /%category%/%postname%/ can also be a good choice
A second good choice for many websites is category/post name:
If you use categories consistently, this can work well. If you may need to change your category structure in the near future, or if you put posts into more than one category, this might not be best. Its SEO value is considered negligible except for the fact that a hierarchical organization of posts makes it easier for search engines to crawl and index your site, which may give you at least a little SEO benefit.
Permalinks and SEO
In general, search engines prefer friendly URLs — those with readable words. So right off the bat, using pretty permalinks will help your SEO. And URLs that contain relevant keywords may help you rank better in search engines.
But the biggest search engine boost most likely will come from writing post titles and post slugs with relevant keywords, and using the simple %postname% structure.
As mentioned earlier, a permalink structure including %category% — assuming the website uses an orderly hierarchical system of categories — makes it easier for search engines to crawl and index your content, which should also help a bit with SEO.
If you absolutely must change the permalink structure of an established website
If you feel it’s necessary to change the permalink structure of an established website with lots of posts, it can be done without causing broken links; it just takes a little work. The method for doing this is beyond the scope of this article, but in short, you edit your website’s .htaccess file, creating a 301 Permanent Redirect which redirects traffic from the old URL to the new URL. This isn’t difficult, but it does have to be done for every post and page on your site.
Making permalinks work for you
The bottom line: if possible, before you begin publish posts — or when you’ve made only a few — make an informed decision about permalinks, make your settings, and stick with it. Then put your energy into writing strong post titles with relevant keywords. With a little thought and effort, both human beings and search engines will like your URLs.