The HTML5 placeholder attribute lets you provide a short hint that helps people enter the right information into a form field.
The hint might be an example of the required information, or a description of the expected format. The placeholder hint or description is displayed inside the empty form field, and is removed as soon as the field is given focus.
<input name="first_name" placeholder="Your first name..." type="text">
The trouble is that once the field is given focus and the placeholder text disappears, there’s nothing left to explain what kind of information should be entered. It’s also inconvenient for keyboard users. Instead of tabbing onto a field and reading the label, they need to look ahead to read the placeholder before moving focus to the field itself