A system resource is a usable part of a computer that can be controlled and allocated by the operating system so that all of the hardware and software on the computer can work together as intended.
The four system resources
System resources can be used by users, such as you, when you open programs and apps, as well as by services that are typically started automatically by your operating system.
You may run out of system resources or even run out of resources because they are limited. Limited access to a particular resource degrades performance and usually results in an error of some sort.
System resources often refer to system memory (your computer's RAM), but resources can also come from the CPU, motherboard, or even other hardware.