 Hi again, in this lesson we're going to talk about that how can we test if a letter in a string is uppercase or lowercase. Let's make some simple example. Let's use a string called myString that contains words Las Vegas. Okay, in our string, first letter has index 0, second letter A has index 1, letter S has index 2, this blank space has index 3 and letter B has index 4, E has index 5, G index 6, A index 7, S index 8, so letter B has index 4 and letter E has index 5. That's enough to remember for now, because we want to test if our letter V is uppercase or lowercase. It's in our string on position with index 4 and we will test that letter with function, with method is upper. This method will return to us through if this letter at index 4, if this letter V is uppercase and it will return false if this letter is lowercase. So let's check it. Okay, this method returns true, which means that letter B is uppercase. Let's check our letter E. It has index 5, so we'll say myString at index 5, is it uppercase or lowercase? Of course, it's lowercase and our method will return to us false. So with this function and with usage of indexes, you can test if your letter in a string is uppercase or lowercase. That's all for this lesson. Thanks for watching. See you in some next lesson. Bye-bye.