What is a sister board on computer?

A sister board in computing refers to a secondary or complementary circuit board that works alongside a primary motherboard to enhance functionality, often by providing additional features or capabilities. These boards can include expansion cards, daughterboards, or other peripherals that connect to the main motherboard, allowing for increased performance or additional functionalities such as graphics processing, networking, or specialized input/output operations. Essentially, sister boards help expand the computer's overall capabilities without replacing the main board.