autocomplete='on' (the default) means browsers may offer to autocomplete the value using pop-ups or what not
autocomplete='off' means they should not, usually for security reasons
Applies to the text, password, date-related, time-related, numeric, email, and url controls
<form>
<p><label>Autocompleting E-mail address:
<input type="email" name="addr"/></label></p>
<p><label>Non-autocompleting e-mail address:
<input type="email" name="addr" autocomplete='off'/>
</label></p>
<p><label><input type="submit" value="Send data" /></label></p>
</form>