Phones and allophones
Phones are phonetic units and appear in square brackets.
When we have a set of phones, all of which are versions of one
phoneme, we add the prefix “allo-” (= one of a closely related
set) and efer to them as allophones of that phoneme.
you should be able to feel somephysical evidence of aspiration
(the puff of air) accompanying the [t] sound at the beginning
of tar (but not in star).
We can represent this nasalization with a small mark (˜), called
“tilde,” over the symbol [ ı̃ ] in a narrow phonetic transcription.
So, there are at least two phones, [i] and [ ı̃ ], used to realize
the single phoneme.