Using checkboxes is a good option when you want to give your visitors the option to choose several units within a group of choices. The type attribute must have the value "checkbox" and then you have to make sure that every checkbox within the same group have the same name. The value of the value attribute is the string that is being sent to your email, to the database or however you choose to use the input.
<input type="checkbox" name="your-group" value="unit-in-group" />Unit-in-group
Checkboxes is a suitable choice when you want to present a lot of options to the user and give them the opportuniti to choose one or more items. Here is an example for those who cannot choose between their favourite pets:
<form method="post"> <fieldset> <legend>What is Your Favorite Pet?</legend> <input type="checkbox" name="animal" value="Cat" />Cats <br /> <input type="checkbox" name="animal" value="Dog" />Dogs<br /> <input type="checkbox" name="animal" value="Bird" />Birds<br /> <input type="submit" value="Submit now" /> </fieldset> </form>