Default WordPress URL structure i.e. permalink structure is not considered as SEO friendly. Search engine likes permalinks with post name as slug in them.
SEO friendly URL structure increases your chance of better ranking on search engines like Google etc. Likewise search engines are the largest source of traffic to popular blogs and organic traffic also gives you better ad revenue.
A SEO friendly URL structure is a user-friendly URL structure in which a visitor can know where he is going to simply by looking at the URL. This also works for search engines as well.
Select SEO Friendly Permalinks In WordPress
Visit your admin area dashboard Settings -> Permalinks admin page and you will see a few permalink options:
- Default http://yourdomain.com/?p=123
- Day and name http://yourdomain.com/2015/09/08/sample-post/
- Month and name http://yourdomain.com/2015/09/sample-post/
- Numeric http://yourdomain.com/archives/123
- Post name http://yourdomain.com/sample-post/
- Custom Structure http://yourdomain.com/%postname%/
URL structure of post name i.e. http://yourdomain.com/sample-post/ is considered as most SEO friendly but you may also use some other permalink structure other than default and numeric as they are neither user-friendly nor SEO friendly, they are simply robotic type URL structures.
If you are doing this on your new WordPress website then its well and good. Otherwise it may cause some 404 errors from search engines and websites linking back to you.
You can easily resolve this problem by redirecting your old permalinks to new ones. Read: “Change Permalink Structure Then Redirect Old Permalinks To New Ones“.