Working with files is one of the first things you do in almost every Python project: open a CSV for a grade list, create a folder for uploads, find every .py file in a project, or build a path that works on both Windows and Linux. For years the usual tools were os.path and plain strings. Today the cleaner option is the built-in pathlib module and its Path objects.

If you have written Java for a while, you have probably written the same loop a hundred times: go through a list, check a condition, add matching items to a new list, then compute a total or an average. The Java Stream API lets you write that kind of code in a few readable lines, and it is used everywhere in modern Java, from Spring Boot projects to coding interviews.

Sooner or later every programmer needs to find a pattern inside text: pull the dates out of a log file, check if an email address looks valid, clean up extra spaces in a name, or turn a title into a URL slug. You could write loops and if statements for each case, but there is a much shorter way: regular expressions (regex). Python supports them through the built-in re module, so there is nothing to install.