why should you learn to write programsthat is more than you really need to know to be python programmerbut sometimes it pays to answer those little nagging questions right at the beginning writing program typing commands into the python interpreter is great way to experiment with python' featuresbut it is not recommended for solving more complex problems when we want to write programwe use text editor to write the python instructions into filewhich is called script by conventionpython scripts have names that end with py to execute the scriptyou have to tell the python interpreter the name of the file in command windowyou would type python hello py as followscat hello py print('hello world!'python hello py hello worldthe "$is the operating system promptand the "cat hello pyis showing us that the file "hello pyhas one-line python program to print string we call the python interpreter and tell it to read its source code from the file "hello pyinstead of prompting us for lines of python code interactively you will notice that there was no need to have quit(at the end of the python program in the file when python is reading your source code from fileit knows to stop when it reaches the end of the file what is programthe definition of program at its most basic is sequence of python statements that have been crafted to do something even our simple hello py script is program it is one-line program and is not particularly usefulbut in the strictest definitionit is python program it might be easiest to understand what program is by thinking about problem that program might be built to solveand then looking at program that would solve that problem lets say you are doing social computing research on facebook posts and you are interested in the most frequently used word in series of posts you could print out the stream of facebook posts and pore over the text looking for the most common wordbut that would take long time and be very mistake prone you would be smart to write python program to handle the task quickly and accurately so you can spend the weekend doing something fun for examplelook at the following text about clown and car look at the text and figure out the most common word and how many times it occurs