Kit

An electronic kit is generally a package of electronic components, an electronic schematic, assembly instructions and often a PCB (printed circuit board).

Background
People primarily purchase electronic kits to have fun and learn how things work. It is convenient to be able to purchase all the parts, the instructions and an already etched PCB as a single package. Kits were once popular as a means to reduce the cost of buying goods, but there is usually no cost saving in buying a kit today. Building devices from scratch has also fallen in popularity partly due to the increasing complexity of surface mount technology and embedded software.