where do you use this?

Answer 1

Python is usually not the language which can help you to make a program completely rather it has implementations in other coding languages and by learning a few others you can make a program which you can use on a daily basis and all. But Python can help you write programs as well by itself but it won't be as flashy if you used a few several others including Python to make a program or an application. Hope this answers your question.

Answer 2

you can create a game, it will help you in studying css further

Answer 3

It's main idea of programming, work, reorganize, read and save user data. Open and close files of the user is the same as work with data gained from other sources, but uses a lot more times than it would be typed by user itself.

Answer 4

With python u can also:
Create websites with django
Work with big data
Work with statistic
Create chat bots
With special frameworks python can be a good friend for 2d , 3d physics models

Maybe i dont understand your question right, so just write what u want to know here? Opening and closing files?