Libraries are collections of shared code. They're common in Python, where they're also called "modules," but they're also ...

Interested in learning Python? Jack Wallen takes you through your first steps in building a simple application to take user input and write it to a file.

One more note: Python is ruthlessly obedient. If you just spent 20 hours running a program and you save the file as temp_data.txt. Then later you run something and save it as temp_data.txt - done.