C# Attributes

Learn what attributes are in C#, how to apply them to code elements, and how to create your own custom attributes.

What is an Attribute?

An attribute is a piece of metadata attached to a code element, such as a class or method, providing additional information that tools or the runtime can read.

Applying Attributes

An attribute is applied by placing it in square brackets directly above the code element it describes, such as [Obsolete] above a method declaration.

Common Built-in Attributes

C# includes many built-in attributes, such as Obsolete for marking deprecated code and Serializable for marking classes that can be converted into a storable format.

Creating Custom Attributes

A custom attribute is created by defining a class that derives from the Attribute base class, allowing you to attach your own application-specific metadata to code.