Each form element must have a programmatically associated label element. You can do so by using an implicit , explicit , aria-label or aria-labelledby.
<label><input type="text" /></label>
<input aria-label="test" type="text" />
<input aria-labelledby="#id" type="text" />
<label for="id"></label><input aria-labelledby="#id" id="id"/>
<input type="image" />
<input value="1" type="text" />
<textarea value="ad"></textarea>