Generally, the collar of a shirt is like the rear-view mirror of your car. You look at it, but you don't really study it, per se. In reality, though, not all shirt collars are the same, and they serve different functions. This shirt-collar taxonomy will help you know what goes with what. Warning: collars in drawings are larger than they appear.
  1. The collar of a shirt should be proportionate to the width of the tie and the lapels. Wider tie, wider lapels, larger collar.
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  2. Skinny tie, skinny lapels, smaller collar.
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  3. One exception: "Billy" from Battlestar Galactica, whose signature tiny tie with huge collar made everyone fall in love. We all wept at his untimely death. Lords of Kobol, may he rest in piece in eternal sartorial wierdness.
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  4. Oxford-Cloth Button Down. Not all white shirts are created equal. There are "dress shirts," made out of poplin - they are very soft and fine and sort of see-through. Then there are OCBDs. The cloth is heavier, thicker, with easily seen weave.
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    It's a bit more preppie/professor/work-shirt and less "banker, executive." With an OCBD, you can pair with a knit tie, purposely NOT button down the collar, and while you're at it, leave the top shirt-button open for a touch of sprezzatura. You can look like you just worked a full day, even if it's only 10am!
  5. Spread collar shirts have no buttons and their points are - wait for it - more spread out than regular collars. They are typically more formal and fancy than their counterparts.
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  6. Unless you are the Merovingian, I don't think you need to worry about spread collars.
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  7. Peter Pan collar (aka Club Collar)
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    The little, round collar can give your outfit an "I work in a 1920s pharmacie" look. If that's what you're going for.