What do the specifications say about the placeholder?
placeholderattribute represents a short hint (a word or short phrase) intended to aid the user with data entry when the control has no value. A hint could be a sample value or a brief description of the expected format.
<label for="email-address">Email</label> <input type="email" id="email-address" name="email-address" placeholder="firstname.lastname@example.org" />
The function of the
placeholder attribute is very different from that of
<label>: a label is a title of the form control and it must always be present, the placeholder is just a help hint in certain fields and it may or may not exist. Different elements to fulfill different functions.
So when you are doing the HTML of the forms, remember that: there is no case where placeholder can replace label.