override

Override is the act of taking precedence over an existing rule, value, or implementation. In computing, to override specifically means providing a new implementation that supersedes the one defined in a more general context, such as in a subclass or configuration.

In object-oriented programming, method overriding allows a subclass to customize or extend inherited behavior. The overriding method must have the same name and a compatible parameter list as the base method. The return type is often constrained to be compatible as well (covariant returns are allowed in some languages). Runtime dispatch determines which version to call, enabling polymorphism. Different languages imitate this differently: Java and C# use explicit keywords or annotations (override or @Override); C++ relies on virtual functions; Python uses standard method definitions with no keyword.

Override is distinct from overloading. Overriding involves the same method signature with a new implementation in a subclass and is resolved at run time. Overloading means multiple methods share the same name but differ in parameter types or counts, and is resolved at compile time in many languages.

Beyond classes, override applies to configurations and rules in software systems. An override can allow a user, environment, or policy to supersede a default setting, feature flag, or access control rule. In some domains, explicit override mechanisms are documented to avoid confusion between inherited behavior and customized behavior.