Aadhaar is a 12-digit Unique IDentification (UID) number which the Unique Identification Authority of India (UIDAI) will issue for all indian residents. literal meaning of aadhaar in english is "support" .as per name , it will give support to poor people .The aadhaar UID number will be stored in a centralised database and linked to the basic demographics and biometric information – photograph, ten fingerprints and iris – of each indian individual. 


For biographic and demographic proof , the information collected will be:

• KYR fields: name , address, gender ,date of birth
• name and address verification document
• Photo
• 10 fingerprints
• iris image

get more info here: What is Aadhar UID card