User ID - definition
User ID stands for User Identification, is the login credential for a website/portal or an app. User ID is unique information which is compulsory to create any account in any portal or site. It also requires a password along with in order to secure the ID or account. Few sites or portal asks user to enter the email address as the UserID because email IDs are unique across the globe or it could be such as CoolNinja23.
