How to convert all strings in a list to integers in Python?

I have a list of strings in Python, and I want to convert all of them to integers. I’ve tried using the int() function, but it only works for individual strings, not for a list of strings.
Here’s my code:

Is there a better way to convert a list of strings to integers in Python?

Also, if possible, can someone explain why we need to convert strings to integers in the first place? Thank you for any help you can provide.