[Serializable]

This is an attribute in C# that indicates that a class can be serialized. Serialization is the process of converting an object into a format that can be stored or transmitted across a network. By marking a class as serializable, you are indicating that an instance of the class can be transformed into a stream of bytes that can then be saved to a file or sent over a network. This attribute is typically used when creating custom classes that need to be persisted or transmitted between different systems or applications.