Hey @kartik,
Scope Parameter is a collection of various symbol that is used to  communicate between isolated scope and its parent scope.
The Various Scope Parameter are- {@,=,&}
1. @
-        It is used to pass the string value to the directive scope
-        One way to the directive scope
-        String could be interpolate string.
2.=
-        It is used to pass an object to the directive scope.
-       Two way binding between parent and directive scope
3.&
-       It is used to enable function to be access to its directive scope. 
-      Directive can executed the function passed to it.
There is another way to communicate between isolated scope and its parent scope simply by using $parent but this is not good practice to access data of parent scope.