Difference between "throw" and "throw ex" in C#

throw : If we use "throw" statement, it preserve original error stack information. In exception handling "throw" with empty parameter is also called re-throwing the last exception.

throw ex : If we use "throw ex" statement, stack trace of exception will be replaced with a stack trace starting at the re-throw point. It is used to intentionally hide stack trace information.

catch (Exception ex)
{
    // do some stuff here
    throw; // a) continue ex
    throw new MyException("failed", ex); // b) wrap
    throw new MyException("failed"); // c)  replace
    throw ex; // d)  reset stack-trace
}

So it is good practice to use the "throw" statement, rather than "throw ex" because it will give us more accurate stack information rather than "throw ex".