The most common and easiest PCB vias are through-hole vias. Though-hole vias are drilled from the PCB's upper layer to the bottom layer. When you take a PCB and look at it facing the light, the holes where light passes through are the through-hole vias.
Though-holes vias are mainly PTH (plating through-hole) vias, and some are the NPTH (non-plating through-hole) vias. PTH vias are used for PTH assembly or electrical connection between different PCB layers, while NPTH is used for mechanical connection with screws or connectors to fix the PCB.
How do you distinguish PTH and NPTH vias? It's easy. Just look at the hole wall to see whether it is electroplated or not.
Though-hole vias cost the lowest but take much PCB space. If the circuit connection is not from the upper layer to the bottom layer, you can turn to other PCB via types to save space.