throw keyword. it is used to user rethrow Exception to caller.its at a time only one exception we can throw.But throws key word is method signature level it will be send multible Exception to the caller
example:

throws:

void meth() throws IOException,ServletException
{
}

throw:

void meth()
{
new throw("user Exception message");
}

Difference between throw and throws

throw is used to throw an exception manually, where as throws is used for checked exceptions, to re-intimate the compiler that we have handled the exception. So throws is to be used at the time of defining a method and also at the time of calling that function, which rises an checked exception it gives the compile time error. Use throws to define our own exception or handle the exception the exception by try-catch, otherwise it gives the compile time error.