::placeholder CSS pseudo-element

The ::placeholder pseudo-element represents placeholder text in an input field: text that represents the input and provides a hint to the user on how to fill out the form. For example, a date-input field might have the placeholder text `YYYY-MM-DD` to clarify that numeric dates are to be entered in year-month-day order.

:placeholder-shown CSS pseudo-class

Input elements can sometimes show placeholder text as a hint to the user on what to type in. See, for example, the placeholder attribute in HTML5. The :placeholder-shown pseudo-class matches an input element that is showing such placeholder text.

input placeholder attribute

Method of setting placeholder text for text-like input fields, to suggest the expected inserted information.

htmlinputelement api: placeholder

html element: input: placeholder