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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
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a single Python file (although it certainly can). Nor does it mean
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that Flask is lacking in functionality. The "micro" in microframework
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means Flask aims to keep the core simple but extensible. Flask won't make
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many decisions for you, such as what database to use. Those decisions that
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it does make, such as what templating engine to use, are easy to change.
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Everything else is up to you, so that Flask can be everything you need
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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 extensions add such functionality to your
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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 the
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possibilities are endless.
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Convention over Configuration
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-----------------------------
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Flask is based on convention over configuration, which means that many things
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are preconfigured. For example, by convention templates and static files are
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stored in subdirectories within the application's Python source tree. While
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this can be changed you usually don't have to. We want to minimize the time
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you need to spend in order to get up and running, without assuming things
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about your needs.
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Growing Up
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----------
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Since Flask is based on a very solid foundation there is not a lot of code in
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Flask itself. As such it's easy to adapt even for large applications and we
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are making sure that you can either configure it as much as possible by
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subclassing things or by forking the entire codebase. If you are interested
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in that, check out the :ref:`becomingbig` chapter.
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If you are curious about the Flask design principles, head over to the section
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about :ref:`design`.
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For the Stalwart and Wizened...
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-------------------------------
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If you're more curious about the minutiae of Flask's implementation, and
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whether its structure is right for your needs, read the
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:ref:`advanced_foreword`.
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