Surface-mount technology (SMT) is a method for producing electronic circuits in which the components are mounted or placed directly onto the surface of printed circuit boards (PCBs). An electronic device so made is called a surface-mount device (SMD). In the industry, it has largely replaced the through-hole technology construction method of fitting components with wire leads into holes in the circuit board.
Both technologies can be used on the same board for components not suited to surface mounting such as large transformers and heatsinked power semiconductors.
An SMT component is usually smaller than its through-hole counterpart because it has either smaller leads or no leads at all. It may have short pins or leads of various styles, flat contacts, a matrix of solder balls (BGAs), or terminations on the body of the component.
and because of that sometimes we don't find an IC with DIP packing as we need to place it on the breadboard for that we need an SMD to DIP socket or adapter and with this SOT89 SOT223 To DIP PCB Adapter Transfer Board we can do that and this is for SOT89 SOT223 where you can place them on the board easily after soldering.