Basically, fingerprint locks operate by scanning and converting your fingerprint data into a numerical template. You can also get more information about the fingerprint door locks through various online sources.
Once you place your finger onto the scanner for the first time the conversion into numerical data takes place, and the fingerprint template is saved. This process is then repeated every time you want to grant someone access.
The next time someone places his/her finger on the sensor, it matches the data obtained through the finger with the pre-saved values. If a match is found, access is granted and the door opens.
On the other hand, if its someone else trying to get through, access is not allowed and the door remains locked.
Now, matching the algorithm is the most important process here. While matching, the already stored fingerprint template is compared to the received input. If there is a match, a green LED usually signals it and the door is opened.
The process is very quick and is completed in a fraction of a second.