Many types of semiconductors are sold as part of circuits, often on an IC. These circuits are usually capable of carrying out any of a number of different functions in a device. This differentiates them substantially from discrete semiconductors.
A discrete semiconductor has a basic function that cannot be divided into other functions. An IC, for example, may have a transistor, a diode, and other components on it. These components can all perform different functions on their own or, working in conjunction as a circuit, can complete several functions together. A discrete semiconductor, however, can only perform one function. For instance, a transistor is always a transistor and can only perform transistor functions.
In today's world, most semiconductors are purchased as part of integrated circuits. For some applications, however, a discrete semiconductor provides the most appropriate possible solution to an engineering need. Therefore, discrete semiconductors have a crucial role in the electronic components marketplace.
As these are discrete devices, some of them need to be purchased along with other devices to achieve the desired functionality for which they are intended in any given circuit. Semiconductor devices perform functions ranging from regulating power to working as switches, and more. For some engineering needs, the ability to purchase discrete semiconductors makes prototyping and production affordable.