The Unique Identification Authority of India (UIDAI) issues a 12 digits unique identification number known as Aadhaar number for every Indian citizen on behalf of the government of India. All individuals can enroll for an Aadhaar card as it serves purpose of an address proof and that of an identification proof. You can eassily apply from here (HM E-Seva). Children, as well as adults, who are eligible to apply for an aadhaar card, can apply for one however; the process can be a little lengthy. The primary thing that should be kept in mind is that registration of aadhaar card is completely voluntary and even if you have not gotten yourself registered, you can still avail of all the privileges that you are eligible for. Secondly, in order to issue the aadhaar card, the individuals need to visit the enrollment center and submit all the required documents and biometric documents firt.