People write programs to execute algorithms, as described in the Algorithms section of this book. Algorithms are implemented using program instructions that are processed during program execution. Program instructions are executed sequentially. Program instructions may involve variables that are initialized and updated, read and written.
An understanding of instruction processing and program execution is useful for programming. Program execution automates processes. Processes use memory, a central processing unit (CPU), and input and output. A process may execute by itself or with other processes. A process may execute on one or several CPUs.
Executable programs increase the scale of problems that can be addressed. Simple algorithms can solve a large set of problems when automated. Improvements in algorithms, hardware, and software increase the kinds of problems and the size of problems solvable by programming.
