<form action="form.php" method="post">
    <input list="cars" name="cars" >
    <datalist id="cars">
        <option value="Volvo">
        <option value="BMW">
        <option value="Bugatti">
        <option value="Cadillac">
        <option value="Chevrolet">
        <option value="Chrysler">
    </datalist>
    <input type="submit" />
</form>