Many Facebook Applications need Facebook Page ID and Profile ID now-a-days. If you are using a custom username for your Facebook profile or page, then unique profile ID will not appear. You can enter custom username where profile ID may be required. Facebook Like Box and some other plugins require this unique ID.
Below I mentioned two easy and simple steps to find the Facebook Profile or Page ID. In this tutorial, I have used Mozilla Firefox and it is recommended!
LOCATE FACEBOOK PROFILE ID – PROCEDURE