An enrollment number in Aadhaar is a 28-digit unique identification number assigned to each Aadhaar applicant. It is assigned when you apply for an Aadhaar card and is used as a temporary reference for your enrollment. The first 14 digits of the enrollment number are randomly assigned, while the next 14 digits show the date and time of your Aadhaar enrollment. You will be given an acknowledgement slip with your enrollment ID on it, which you can use to track the status of your Aadhaar application and get details about your enrollment from the Aadhaar database. If you forget your enrollment ID, you can retrieve it by visiting the UIDAI website and selecting "Enrollment ID". You will need to enter your name, mobile number or email address, and captcha, and then click on "Get One Time Password" and enter the OTP received on your mobile number or email address.