The ATX form factor is a standard specification for motherboards and cases in desktop computers. Introduced by Intel in 1995, it defines the dimensions, mounting points, power connections, and I/O panel layout. The standard size is 305 mm x 244 mm (12 in x 9.6 in), allowing for better airflow and component arrangement. ATX motherboards typically support multiple expansion slots, enabling users to add graphics cards, sound cards, and other peripherals. This form factor has evolved into various derivatives, such as MicroATX and Mini-ITX, which offer smaller sizes while maintaining compatibility with ATX cases and power supplies.