HTML5 provides some options to check inputs before sending it to the server, respectively to help users to fill a form with useful values. Such help and control was performed before with java-script, therefore a big progress to get rid of scripting and to replace it with declarative methods. On the other side, because all this input can be manipulated, one has to check all inputs finally at the server again.
Fill the form, you will see your input after sending:
In HTML5 it is possible to place form input elements outside the form element, just indicating the relation to the form.
Do not provide the required value and use wrong input values and send the form without validation: