As you remember from last time, a computer is considered a universal information manipulator. It is universal because it can do many different kinds of things, depending on which instructions are stored in memory. This list of instructions is called a program. Programs are also referred to as software. So far, we have been pretty theoretical about how computers work, but we know that besides the software, they do have a physical entity. The physical pieces you can see are referred to as hardware. A computer system is a combination of both hardware and software.