The multiple attribute is applied to a form field element to indicate that more than one value can be selected at a time. The exact behavior of the multiple attribute depends on the context in which it is applied.
<input type="text" list="suggestions" multiple />
<input type="file" multiple />
<select multiple />
When applied to a select element, the element is displayed as a container displaying multiple entries which can be toggled as selected or not selected.
When applied to a standard input element which is associated with a datalist element by way of a list attribute, additional items selected from the set of suggested values will be appended to the value of the text box, delimited with a comma.
When applied to an input type=”file” element, the multiple attribute allows multiple files to be selected within the file selection dialog.
The attribute multiple example: