Operating systems provide various shell commands that we can use to communicate with I/O devices. Shell commands are examples of programs that are built-in to the operating system. Operating systems also allow us to create our own programs and run them in the shell.

A program is just a set of computer intructions. To create a program, we write a bunch of instructions using a text editor such as Notepad and save the instructions to a file. We can execute the program in 1 of 2 ways:

1. Run the program file directly in the shell.
2. Supply the program file path to a special shell command that can interpret the program.

In this chapter, we are going to write and execute Python programs in LWOS. Python programs require the interpreter to run. The Python interpreter is included in LWOS, so we can continue to use the LWOS simulator to test Python programs.