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Foreword
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========
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Read this before you get started with Flask. This hopefully answers some
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questions about the purpose and goals of the project, and when you
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should or should not be using it.
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What does "micro" mean?
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-----------------------
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“Micro” does not mean that your whole web application has to fit into a single
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Python file (although it certainly can), nor does it mean that Flask is lacking
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in functionality. The "micro" in microframework means Flask aims to keep the
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core simple but extensible. Flask won't make many decisions for you, such as
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what database to use. Those decisions that it does make, such as what
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templating engine to use, are easy to change. Everything else is up to you, so
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that Flask can be everything you need and nothing you don't.
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By default, Flask does not include a database abstraction layer, form
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validation or anything else where different libraries already exist that can
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handle that. Instead, Flask supports extensions to add such functionality to
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your application as if it was implemented in Flask itself. Numerous extensions
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provide database integration, form validation, upload handling, various open
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authentication technologies, and more. Flask may be "micro", but it's ready for
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production use on a variety of needs.
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Configuration and Conventions
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-----------------------------
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Flask has many configuration values, with sensible defaults, and a few
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conventions when getting started. By convention, templates and static files are
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stored in subdirectories within the application's Python source tree, with the
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names :file:`templates` and :file:`static` respectively. While this can be changed, you
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usually don't have to, especially when getting started.
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Growing with Flask
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------------------
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Once you have Flask up and running, you'll find a variety of extensions
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available in the community to integrate your project for production. The Flask
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core team reviews extensions and ensures approved extensions do not break with
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future releases.
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As your codebase grows, you are free to make the design decisions appropriate
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for your project. Flask will continue to provide a very simple glue layer to
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the best that Python has to offer. You can implement advanced patterns in
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SQLAlchemy or another database tool, introduce non-relational data persistence
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as appropriate, and take advantage of framework-agnostic tools built for WSGI,
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the Python web interface.
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Flask includes many hooks to customize its behavior. Should you need more
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customization, the Flask class is built for subclassing. If you are interested
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in that, check out the :ref:`becomingbig` chapter. If you are curious about
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the Flask design principles, head over to the section about :ref:`design`.
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Continue to :ref:`installation`, the :ref:`quickstart`, or the
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:ref:`advanced_foreword`.
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