Aadhaar is a 12-digit unique number issued to all Indian residents by the Unique Identification Authority of India (UIDAI). It is stored in a centralized database and is linked to basic demographics and biometric information for identification purposes. Aadhaar aims to provide a universal identity system that eliminates duplicate and fake identities. To obtain an Aadhaar, an individual needs to submit required documents and undergo biometric scanning at an enrollment camp. The enrollment process involves filling a form with details like name, address, and photo followed by fingerprint and iris scans.