Content that includes form controls.
The objective of this technique is to provide a mechanism that allows users to explicitly request changes of context. The intended use of a submit button is to generate an HTTP request that submits data entered in a form, so it is an appropriate control to use for causing a change of context.
<form action="/subscribe" method="post">
<p>Enter your email address to subscribe to our mailing list.</p>
<label for="address">Your email address:</label>
<input autocomplete="email" id="address" name="address" type="text">
<input type="submit" value="Subscribe">
</form>
<input type="submit">, <input type="image">, or <button type="submit">).