The multiple attribute on a <select> tag specifies that multiple items can be selected.
With this attribute, the control appears like a scrollable list, rather than a dropdown.
A multiple attribute on a <select> tag.
Multiple cities can be selected with a Ctrl-click or Shift-click key combination.
Notice that instead of a dropdown, the select appears in list form.
<form action="/tutorial/fileupload.html">
<select multiple style="height:125px;" name="cities">
<option value="paris">Paris</option>
<option value="london">London</option>
<option value="athens">Athens</option>
<option value="madrid">Madrid</option>
<option value="berlin">Berlin</option>
</select><br />
<input type="submit">
</form>
A <select> element with a multiple attribute accepts multiple selections.
With this attribute present, users can select one or more items.
Multiple items are selected with Ctrl-click or Shift-click key combinations.
Ctrl-click adds individual items, Shift-click adds a range of items.
Tip: With multiple items selected, the client sends multiple name/value pairs to the server with the same name. With server frameworks like ASP.NET, PHP, or Ruby you will need to add square brackets [] at the end of the name. The server will then place the item values in an array by that name.
<select multiple>
Here is when multiple support started for each browser:
 Chrome
|
1.0 | Sep 2008 |
 Firefox
|
1.0 | Sep 2002 |
 IE/Edge
|
1.0 | Aug 1995 |
 Opera
|
1.0 | Jan 2006 |
 Safari
|
1.0 | Jan 2003 |
