This section describes some of the basic computer science concepts and introduces the terminology used in computing professions. Hardware is what most people think of as a computer. It is the physical machine broken down into its components. For a PC, the CPU, main memory, and the storage devices are normally housed in a single cabinet. Older Macintoshes and the newer iMac also include a monitor in the cabinet.
Software is what makes the computer useful.
Normally, a user interacts with a computer through a piece of software called the operating system . This is the software that allows a user to run a program, manage their files, etc. When we run a program, the program along with some data from the user is loaded into the computer's main memory, then we say the computer executes the program on the data. This usually results in some output showing the results. A program is a set of instructions.