Electronic Kit Definition as from Wikipedia
An electronic kit is a package of electrical components used to build an electronic device. Generally, kits are composed of electronic components, a circuit diagram (schematic), assembly instructions and often a printed circuit board (PCB) or another type of prototyping board.
There are 2 distinct types of kit, those that will construct a single project, and those that can construct a range of projects. The latter are primarily aimed at children, and include a solderless construction board of some type, such as;
Components mounted in plastic blocks with side contacts, that are held together in a base, e.g. Denshi blocks
Springs on a card board, the springs trap wire leads or component leads, such as Philips EE electronic experiment kits. These are a cheap and flexible option,
Professional type prototyping boards, (breadboards) into which component leads are inserted, following documentation of the “kit”.
The first type of kits, those for the construction of a single device, normally use a PCB on which components are soldered. They normally come with extended documentation describing which component goes where into the PCB.
People primarily purchase electronic kits to have fun and learn how things work. They 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.
Some kits used to be quite complex devices such as color television sets, oscilloscopes, high-end audio amplifiers and even computers such as the Heathkit H-8, and the LNW-80. Many of the early microprocessor computers were sold as either electronic kits or assembled and tested. Heathkit sold millions of electronic kits during its 45-year history.
Today, building devices from scratch for hobbyists and beginners has fallen in popularity due partly to the emerging complexity of miniature electronics and embedded software. People still build custom devices and special-purpose electronics for professional and educational use, and as a hobby.
Also emerging is a trend to simplify the complexity by providing preprogrammed or modular kits and this is provided by many suppliers online often. The fun and thrill of making your own electronics has shifted in many cases from easy to comprehend application and analog devices to more sophisticated and digital devices.