@Alex Akyuz all the options are biometric. Fingerprint Scan - Not so secured, can be spoofed. There are different techniques and technologies to spoof it. (As seen in movies) Palm Vain - next best thing after Fingerprint. But, this too can be spoofed with little difficulty. Iris Scan - looks at the ring around your eye. Little bit non-intrusive. Can also be manipulated using new techniques like lenses etc. Retena scan - looks at the retina inside your eye. For this you need to keep your eye open & steady before a scanner for a period of time. More intrusive & extremely hard to spoof. Iris & retena scans can be considered like the fingerprint & palm vein scans of hand. I added pictures below that helps you understand.