Final answer:
Expansion cards are removable circuit boards used to expand a motherboard's capabilities, consisting of an integrated circuit or microchip. They serve different functions like enhancing graphics or sound and fit into standardized motherboard slots.
Step-by-step explanation:
The removable circuit boards that are inserted into slots on the motherboard to expand the motherboard's capabilities are called expansion cards or expansion boards. These boards are a type of integrated circuit, which consists of transistors etched onto a piece of silicon, often referred to as a microchip. The invention of microchips allowed for the significant downscaling of computer technology, contributing to the development and spread of personal computers. Expansion cards can serve various functions, such as improving graphics, sound, or network capabilities, and are designed to be interchangeable, fitting into standardized slots on the motherboard.