In the 26-bit Wiegand format, bit 1 is an even parity bit. Bits 2–9 are a facility code. Bits 10–25 are the card number. Bit 26 is an odd parity bit. 1/8/16/1. Other formats have a similar structure of a leading facility code followed by the card number and including parity bits for error checking, such as the 1/12/12/1 format used by some American access control companies.

A contactless smart card uses the same radio-based technology as the proximity card, with the exception of the frequency band used: it uses a higher frequency (13.56 MHz instead of 125 kHz), which allows the transfer of more data, and communication with several cards at the same time. A contactless card does not have to touch the reader or even be taken out of a wallet or purse. Most access control systems only read serial numbers of contactless smart cards and do not utilize the available memory. Card memory may be used for storing biometric data (i.e. fingerprint template) of a user. In such case a biometric reader first reads the template on the card and then compares it to the finger (hand, eye, etc.) presented by the user. In this way biometric data of users does not have to be distributed and stored in the memory of controllers or readers, which simplifies the system and reduces memory requirements.
Sometimes memories can fade in time, but then we can experience something which brings decade’s old memories flooding back. It could be finding an old photograph, the feel of something in our fingers, the sound of seagulls squawking overhead or the smell from a bakery wafting in the breeze as we are walking along the street. Then, just for a moment, it is as though we are right back in that once-forgotten moment, experiencing the joy and happiness as though reliving it.