select2/docs/_includes/options/selections/placeholder.html

<section>
  <h2 id="placeholder">
    How can I have Select2 display a placeholder?
  </h2>

  <p>
    Select2 supports displaying a placeholder by default using the <code>placeholder</code> option. This can be either a data object matching the placeholder option, or a string to display as the placeholder if you are using a blank placeholder option.
  </p>

  <h3>
    My first option is being displayed instead of my placeholder
  </h3>

  <p>
    This usually means that you do not have a blank <code>&lt;option&gt;&lt/option&gt;</code> as the first option in your <code>&lt;select&gt;</code>.
  </p>

  <p>
    Note that this does not apply to multiple selects, as the browser does not select the first option by default when multiple selections can be made.
  </p>

  <h3>
    I am using AJAX, can I still show a placeholder?
  </h3>

  <p>
    Yes, Select2 supports placeholders for all configurations. You will still need to add in the placeholder option if you are using a single select.
  </p>

  <h3>
    Can I use an option without a blank value as my placeholder?
  </h3>

  <p>
    The <code>placeholder</code> option allows you to pass in a data object instead of just a string if you need more flexibility. The <code>id</code> of the data object should match the <code>value</code> of the placeholder option.
  </p>

  <h3>
    Can I change how the placeholder looks?
  </h3>

  <p>
    The placeholder option should go through the standard templating methods, including <code>templateSelection</code>, so you can change how it is displayed.
  </p>

  <h3>
    My placeholders aren&apos;t being displayed in Internet Explorer
  </h3>

  <p>
    Select2 uses the native <code>placeholder</code> attribute on input boxes for the multiple select, and that attribute is not supported in older versions of Internet Explorer. You need to include Placeholders.js on your page, or use the full build, in order to add <code>placeholder</code> attribute support to input boxes.
  </p>
</section>