Example 1
A candy shop just opened up next door to the offices of Jude Schnickelman, D.D.S.
Well, that's convenient… maybe too convenient. In this example, D.D.S. is an abbreviation for the title Doctor of Dental Surgery.
Example 2
According to Google Maps, the pumpkin farm is thirty-five miles away, so we should leave at 8:15 a.m. at the latest if we want to be there when it opens.
We hear those big pumpkins are a hot commodity. Let's carve up this sentence: a.m. is abbreviated because it refers to time; miles isn't because it's a unit of measurement.
Example 3
Graham made his girlfriend a playlist of foot-themed MP3s to listen to while she studies for her podiatry exam.
In this sentence, MP3 is abbreviated to an acronym because it's a familiar object. Podiatry is not because it's an area of study. Now if you'll excuse us, we're going to go listen to Chromeo's "Fancy Footwork" on repeat.