Method overloading means having two or more methods with the same name but different signatures in the same scope. Compiler automatically select the most appropriate method based on the parameter supplied.

public class multiplynumber
{
public int multiply(int x, int y)
{
return x * y;
}
public int multiply(int x, int y, int z)
{
return x*y*z;
} 
}

Clas A
{
Virtual void sum (int a)
{
}
}
Class B:A
{
public overrid void sum (int a)
{
}
}