Why Your Permalinks Matter: And How to Fix Them
By default, WordPress uses numbers to fins the content in your site. Numbers work great for computers, but names and phrases work best for people.
You’ll find the permalink settings under Settings > Permalinks. The default permalink is ?p=<postid>, but I prefer to use either /post-name/ or /category/post-name/.
For the first option, you change the setting to /%postname%/:
To include the category, you select “Custom Structure” and change the value to/%category%/%postname%/. If you previously had ?p=<postid> as your permalink WordPress will take care of all the redirects for you. This is also true if you change from/%postname%/ to /%category%/%postname%/.