A test probe works in a test fixture board mating an installed probe receptacle. The probe will contact the component on the PCB by compressing to a working travel, then the contact will keep the PCB signal going from the probe to the terminal installed in the Receiver board. 

According to component differentiation, the fixture designer could select relative probe tips to match test points,  here is where you could refer to how to select a probe tip Tips-Selection.

A probe was made to contact a lead to contact bumps, dips, and via holes to check the PCB line was open or short which was judged by the test fixture on the Agilent ICT tester, largely applied probes on test fixtures to check the print circuit boards of desktops, notebooks, and servers in EMS ( Electronics Manufacturing Service) industries.

There are not only the probes on the fixture, but the mated sockets or receptacles were tightly installed on the fixture board to keep a straight plug-in, these receptacles are wrapped in the wires to contact the terminals on the interface board, this is a systematic framework. The receptacle fits tightly with the probe. Operators can maintain the probes by pulling out the useless probes, this will keep the test fixture a long life and save a lot.

With the development of tests, Pads become much smaller and higher density than before. So, it requires higher precision for probes and receptacles.