.. index:: single: Expressions in the Framework
.. versionadded:: 2.4
The expression functionality was introduced in Symfony 2.4.
In Symfony 2.4, a powerful :doc:`ExpressionLanguage </components/expression_language/introduction>` component was added to Symfony. This allows us to add highly customized logic inside configuration.
The Symfony Framework leverages expressions out of the box in the following ways:
- :ref:`Configuring services <book-services-expressions>`;
- :ref:`Route matching conditions <book-routing-conditions>`;
- :ref:`Checking security <book-security-expressions>` and :ref:`access controls with allow_if <book-security-allow-if>`;
- :doc:`Validation </reference/constraints/Expression>`.
For more information about how to create and work with expressions, see :doc:`/components/expression_language/syntax`.