Attributes in .Net framework

Attributes provide additional user-defined metadata. Most commonly, they are used to store additional information about a type in its assembly, or to modify the behavior of a type member in either the design-time or run-time environment. Attributes are themselves classes that inherit from System.Attribute. Languages that support the use of attributes each have their own syntax for applying attributes to a language element. Attributes can be applied to almost any language element; the specific elements to which an attribute can be applied are defined by the AttributeUsageAttribute that is applied to that attribute class.