People who have just played with printed circuit boards as a hobby probably are familiar with through-hole boards. This is an older way of making circuit boards that runs leads through pre-punched holes in the board. It's effective, but it's also more expensive than the newer surface mount technolgy, offten called SMT assembly. Through-hole technology is still used for larger components and components that have to hold up to more hard use. It's also used a lot for prototyping.