When using python IDLE from Python website I found an annoying problem: characters one 1 and lower L l look the same.
Is there a quick and practical way to solve this problem without making the whole text look much different?
Yes, there is!
IDLE uses Courier New as default font.
If you go to Options > Configure IDLE > Fonts/Tabs and change the Font Face: to Consolas, those characters become distinguishable but you keep the average look of the text!
(this is the font used on Windows' Text Notebook).