Built-in Modules
Modules provide namespaces and reusable code. Distinguish modules shipped with Python from external distributions installed into your environment.
Understand the idea
The standard library includes math, statistics, pathlib, json, datetime, collections, and many others. Technically, built-in modules are a smaller implementation category than the whole standard library. importlib can inspect availability without requiring you to guess from a package name. Keep module names in your project from shadowing standard-library imports.
Where to try it
Open this example with Try in playground. The code loads as editable text and does not run until you select Run. The first run downloads Python. Each run starts fresh; temporary files created by a script are not files on your PC.
A worked example
import importlib.util
print(importlib.util.find_spec("json") is not None)
print(importlib.util.find_spec("math") is not None)
Read the result
Both checks are True in the supported runtime.
Try one change
Compare the installed distribution name scikit-learn with the import namespace sklearn.