HTML is the standard markup language for Web pages. With HTML you can create your own Website.
Description
If you have an input field on your website with a font size of fewer than 16 pixels, Safari on iPhone considers the text too small to read and automatically zooms in on the form field when the user taps on it.
The behavior is intended but it can deteriorate the expected user experience so it might be a good idea to disable this functionality and keep the zoom static while filling form controls.