Buttons

What is the purpose of a Lapel Buttonhole?
The lapel was originally meant to be buttoned to the top. Fast forward to today many use it to hold flowers. Some suit makers even sew a loop on the underside of the buttonhole to hold your boutonniere in place. But for everyday wear, the decorative flair is mostly relegated to lapel pins, if used at all. There's only one golden rule for lapel pins: To wear them approximately where the lapel buttonhole is or would be. That's the upper part of the left lapel. Some double-breasted suits have these buttonholes on both lapels, but lapel pins should always go on the left-hand side.
Fun fact
There was a time when men would wear dress hats with an elastic cord with a button on the end. This button on a string was used to fasten to your jacket lapel. Therefore, in windy conditions, you wouldn't lose your hat if it blew off.
Milanese buttonhole
Believed to have originated in Italy and then made popular by Italian tailors in France, the Milanese buttonhole is the apex of a fundamentally tailored suit. It involves a piece of thread called a "gimp" which is hand-stitched to surround the buttonhole.
What are kissing buttons?
Kissing Buttons (also called stacked or "waterfall" buttons) Kissing Buttons are buttons that touch slightly as opposed to being spaced apart. High quality suits will feature sleeve buttons that are kissing and not kissing.
Real Vs Fake Sleeve Button Holes
One of the easiest ways of telling a tailor-made suit from an off the rack bought suit is looking at the sleeve- and lapel buttonholes. A tailor made suit is likely to have a real sleeve and lapel buttonholes, whereas an off the rack suit will always have fake ones. However, remember that a tailored suit can also have fake buttonholes. It's about your taste and preference.
So why do you need real buttonholes, you may ask? Back in the days, you needed real sleeve buttonholes to be able to roll up your sleeves for work, hence the name work and surgeon sleeves. This has changed, and nowadays it's more about style than anything else. Some stylists say you should, as with the suit jacket, leave one button unbuttoned. This is truly a matter of taste; some like the style, some do it to show the world they have a tailored made suit, and others think it is unnecessary and a way of "bragging". If you were to leave one button unbuttoned, it should be the button closest to the hand.