Permalinks are the permanent URLs to your individual pages and blog posts, as well as your category and tag archives. A permalink is the web address used to link to your content. The URL to each post should be permanent, and never change — hence the name permalink.
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.
To change your permalink settings:
On your dashboard click Settings > Permalinks
Select one of the Common Settings (Post name is recommended).