pip is the tool most Python programmers use to install third-party code. Its official documentation states plainly that “pip is the package installer for Python,” and that pip can install packages “from the Python Package Index and other indexes.”
The Python Package Index, known as PyPI, is the large public repository that pip pulls from by default. The combination is familiar: a developer names a package, and pip retrieves that package and its dependencies and installs them into the Python environment. This is the same registry-plus-installer shape seen in npm for JavaScript and Cargo for Rust, applied to Python’s much older ecosystem.
Because the documentation notes that pip can install from “other indexes” as well as PyPI, organizations can run private package indexes and point pip at them, which is how many companies distribute internal Python libraries without publishing them publicly.
pip matters because it is the default on-ramp to Python’s enormous library ecosystem. For most users, installing a Python package and typing a pip command are the same action, which makes pip one of the most widely used pieces of developer tooling in the language.