Definition and Usage

The required attribute is a boolean attribute. When present, it specifies the user is required to select a value before submitting the form. It specifies that the user is required to select an option before submitting the form.We’ll use the required attribute to indicate that we need the user to provide the information requested by this control. When this attribute present, and the control is in the drop-down mode, authors must provide a placeholder label option, which is nothing but a first option that when selected, indicates that no real option has been selected in the control. This option must be the first in the control, its value attribute must be empty and it musn’t belong to any optgroup.

When the required attribute is present, supporting browsers prevent the submission of the form until one or more options in this control have been properly selected.
Possible values:

• [Empty string]
• required