Perform Alphabet validation (Letters) using OnKeyPress in jQuery

Here Mudassar Ahmed Khan has explained with an example, how to perform Alphabet validation i.e. allow only Letters (A-Z) using OnKeyPress event in jQuery. When User types in the TextBox, the text in the TextBox will be validated using OnKeyPress event handler in jQuery and if the inputted character is not Alphabet i.e. Letters (A-Z), the error message will be displayed next to the TextBox.