REF keyword belongs to the family of parameter modifiers in C#. The other
family members include out and in (Added in C# 7.2 and readonly (added in C# 7.2)

 

These modifiers are used as prefixes to indicate that a parameter is passed by reference.The new “ref” keyword in C# 6.0 adds a new level of control when passing parameters
by reference.

unlike “out” which can only be used for output values. This provides more flexibility
in how parameters are passed and manipulated in a method.

public void ModifyValue(ref int x)
{ x *= 2;
} int value = 5;
ModifyValue(ref value); // value will now be 10

 

This allows for more efficient handling of large or
complex data types without creating unnecessary copies. Overall, the “ref” keyword adds a new level of control and flexibility to parameter
passing in C# and can be useful in various scenarios where a method needs to modify
the value of a parameter.