In general, a spring-loaded (Pogo Pin) contact is made of 4 main pieces - a Piston, Body, Spring & End-Cap.
A spring-loaded contact is mainly intended for Board to Board connections. The pin is fixed on one PCB (by solder or press-fit), and another circuit board with a contact pad makes a connection with the pin via mechanical movement (such as a battery cover opening and closing). The conduction path of the contact is connected to the piston, and spring tension ensures that both the piston and the contact pad on the other board are pressed firmly together.
The main advantage of spring-loaded pIns is that they don’t need precise board-to-board alignment, they have higher vibration tolerance than typical connectors, and they have better connectivity over time after board mis-alignment due to long term movement or vibration in the system.
For information on how to mate to spring loaded contacts pins, please refer to: