Backend development

Stage 1 · Lesson 4 of 10

Modules, virtual environments and pip

Your language and how HTTP works

In Python, a file of code is a , and a folder of modules is a package. You bring them in with import or from ... import. Other people's packages come from PyPI, the public package , and you install them with or uv.

Install them into a virtual environment (venv), which is a separate folder of packages for each project. That way two projects can use different versions of the same library. Create one with python -m venv .venv and activate it, or let uv manage it for you. Record your dependencies in pyproject.toml, with a or pinned versions.

Common trapinstalling packages globally: sooner or later two projects need different versions, or a system tool breaks, and "it works on my machine" follows. One environment per project, from day one.

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Resources for this stage

Start with· follow one of these

Practise

  • Exercism

    Your language track: small exercises with free mentor feedback on idiomatic code

Keep handy

  • W3Schools

    Quick syntax lookups for your language when you forget how something is written

  • MDN Web Docs

    Read the HTTP overview, methods, headers and status code pages until they feel obvious

Also worth your time

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