An attribute is a declarative tag that is used to convey information to runtime about the behaviors of various elements like classes, methods, structures, enumerators, assemblies etc. in your program. You can add declarative information to a program by using an attribute.
Attributes are important because they are used to impose conditions or to increase the efficiency of a piece of code.
C # developers are in specific companies eg Provides a way to define notification tags. Class, method are called attributes. Using the mirror, the movement of information can be obtained at the moment.