What is the principle of swipe card to unlock?

[bancroft]

I got interested in swipe cards to unlock after reading an article today, but first I need to figure out two things.

How do swipers identify different cards? And what does the so-called RF mean?

 

[WHONOES]

Why do you want to read swipe card data?

 

[bancroft]

Why do you want to read swipe card data?

I want to implement the function of swipe card unlock, then I want to know whether the reader reads the frequency of the card or ID? or something else.

 

[Harald Kapp]

The classic swipe card uses magnetic strips to encode information and requires a magnetic card reader.
The card in the article you linked to is no such card but an RFID card. An RFID card requires a card reader that emits a high frequency electromagnetic field. This field is picked up by an antenna on the card and used to power the card's microcontroller. Data is transmitted between the reader and the card by modulating the electromagnetic field. See e.g. this tutorial.

 

[bancroft]

The classic swipe card uses magnetic strips to encode information and requires a magnetic card reader.
The card in the article you linked to is no such card but an RFID card. An RFID card requires a card reader that emits a high frequency electromagnetic field. This field is picked up by an antenna on the card and used to power the card's microcontroller. Data is transmitted between the reader and the card by modulating the electromagnetic field. See e.g. this tutorial.

Thank you very much, I think this tutorial helped me a lot and I can understand RFID very well.