A form with an email field that that must be in the following order: characters@characters.domain (characters followed by an @ sign, followed by more characters, and then a ".". After the "." sign, you can only write 2 to 3 letters from a to z:
Click the "Try it" button to display the value of the pattern attribute of the email field.
Note: input elements with type="email" are not supported in IE 9 (and earlier), or Safari.