Readonly ,Const Keyword with static Modifier

Public static readonly fields are a little unusual; public static properties (with only a get) would be more common (perhaps backed by a private static readonly field).

Const values are burned directly into the call-site; this is double edged:

• it is useless if the value is fetched at runtime, perhaps from config
• if you change the value of a const, you need to rebuild all the clients
• but it can be faster, as it avoids a method call...
• ...which might sometimes have been inlined by the JIT anyway

If the value will never change, then const is fine - Zero etc make reasonable consts ;-p Other than that, static properties are more common.

Go through following link for more details

http://www.stum.de/2009/01/14/const-strings-a-very-convenient-way-to-shoot-yourself-in-the-foot/

• const fields has to be initialized while declaration only, while readonly fields can be initialized at declaration or in the constructor.
• const variables can declared in methods ,while readonly fields cannot be declared in methods.
• const fields cannot be used with static modifier, while readonly fields can be used with static modifier.
• A const field is a compile-time constant, the readonly field can be used for run time constants.