While the phoneme is the abstract unit or sound-type( in the mind"), there are many different versions of that sound-type regularly produced in actual speech ("in the mouth"). We can describe those different versions as phones. Phones are phonetic units and appear in square brackets. When we have a set of phones, all of which are one of a closely related set) and versions of one phoneme, we add the prefix "allo refer to them as allophones of that phoneme. For example, the [t] sound in the word tar is normally pronounced with a stronger puff of air than is present in the [tl sound in the word star. If you put the back of your hand in front of your mouth as you say tar, then star, you should be able to feel some physical evidence of aspiration (the puff of air) accompanying the It] sound at the beginning of tar (but not in star). This aspirated version is represented more precisely