User identification is a crucial aspect of online security, and there are various synonyms for the term "User ID" that are commonly used in online platforms. Some alternatives to User ID include login name, username, user handle, and account name. These terms are used interchangeably and often refer to the same thing, which is a unique identifier assigned to an individual to access online services. Other synonyms for User ID include screen name, handle, and alias. These terms add a layer of anonymity to the online identity of users, which can be useful in protecting one's personal information. In summary, User ID has numerous synonyms that are commonly used in online platforms, and all of them serve the same purpose: to identify the user.