What is a C# Attribute?

What is a C# Attribute? 

Real short answer: It is a way of tacking declarative information into C# code (as opposed to something that actually generates code that does something like assigning a variable). You can use reflection to look up attributes. You can use system defined declarations or your own. Syntax uses square brackets such as [System.Attribute]

Common attributes:

1. 
   

   [System.Serializable]

   [Obsolete("Don't use Old method, use New method", true)]
   

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