Someone can use your username or user ID to access into your Facebook account. But unlike usernames, users ids are hard to remember and not human friendly. Normally your Facebook account URL will be look like this:
As you can see, above URL is not user friendly. So you can use a short and simple URL for your Facebook account creating an username.
For example this is my Facebook account URL:
To add your own Facebook username follow the easy steps given below.
1.Login to your facebook account.
3.You can see a screen like below. Click on "More".
4.Now enter your desired username as the example below and click on "Check availability".
If your username available you can get it clicking on "Confirm".
You are done. Now if someone has your username, they can type "facebook.com/yourusername" into their browser and see your public information, as well as anything else they're in the audience for.
File Under : facebook