SMT & PTH

Surface mount technology (SMT), as previously mentioned, involves mounting components directly onto the surface of the PCB, without requiring holes. SMT components are smaller and lighter than through-hole components, and they can be placed more densely on a PCB.
Pin through hole technology (PTH) is another method of attaching electronic components to printed circuit boards (PCBs) that involves inserting component leads through holes in the PCB and then soldering them on the opposite side of the board. This method is similar to through-hole technology, but it is used specifically for components with pins or leads that are larger than those used in typical through-hole components.
In general, SMT technology is preferred over PTH technology for modern electronics due to its smaller size, higher density, and easier automation during manufacturing. However, PTH technology may still be used in certain applications where through-hole components are necessary for strength or mechanical stability, or for components that need to be replaced or serviced frequently.