Hugs are the usual greeting in my group of friends, and are not uncommon among my family and the families of other southern people I know. (some people take this so far as to hug others without asking first, which is horrible) It's also a really common method of comforting via the internet, at least everywhere I have been. But a lot of people don't put any thought into a hug beyond "we encircle each other with our arms and then stop." But there are such a variety of hugs!
the christian side-hug
A hug that involves people being side-by-side and wrapping the near arm around the other person's back, bringing the far arm around to touch the other's far shoulder and leaving a circle of air in between, usually looking away.
The only people I allow to do this to me are my bioparent M and Topaz' family. With my bioparent, it's because they have self-imposed limits of bodily contact with those they perceive as women. With Topaz' family, I let them set the parameters of hugs.
the straight girl A-frame
This is a variant of the christian side-hug where you face each other and put your arma around each other, but do so with your bodies at least a foot apart and your backs arched so that your chests don't touch.
I do not tolerate this kind of hug. I'd rarher have a handshake, or nothing at all.
the limp noodle
This is when someone goes to hug you but doesn't place any firmness into it, holding all of their parts away, barely touching you with their arms and chest, sometimes giving a light tentative pat at the end.
GROSS GROSS GROSS I hate this kind SO MUCH. It makes me feel like I'm covered in slime and you're trying not to get it on you. This kind of hug makes me want to punch whoever is doing it.
the quick squeeze
This is when someone hugs you for about 1.5 seconds - just wrap arms around, give a quick squeeze, and immediately pull away. This is the usual greeting hug among hippies.
I like this one okay. It's better than no touch.
This is when someone hugs you with such a hard squeeze that it could crack your back (or in my case, cause your boobs to ache).
I hate this one. People do not seem to realize that the fact that it feels good to them doesn't mean it feels good to me. There's also a sub-variant, where the person isn't squeezing too hard but is squeezing at the wrong place and it is smashing my boobs. PSA: if you are hugging someone with large breasts, squeeze them around the waist ONLY not around the chest (or ask).
the favorite hug
This varies from person to person I'm sure. For me, there are several elements that make up my favorite hug; time length, emotional presence, arm placement, body height, pressure, hand movement, and above all posture softness.
For length, I prefer longer (in the 8-11 second range usually) but I let the other person end it as quickly as they wish. As soon as they lift their head from my shoulder, drop their hands from my back, or otherwise shift to end the hug, I mirror and let them out of the hug. Otherwise it's not good consent.
To be emotionally present for me means we're silent, eyes closed, fully emotionally focused on each other, not thinking about other things, not hurried.
Position-wise, I prefer to have my right arm over their left shoulder, with my other arm wrapped around their waist and them mirroring - this is an idea passed on to me from someone else that solves a lot of the squishing problems and also is more egalitarian. But one person's arms under the other is a better hug for comforting, I feel - with the person giving comfort having arms on top because they feel like a shield then. I want bodies to be close, either with us sitting next to each other thighs touching, or standing face to face with feet staggered and foot-circles overlapping.
Height should be adjusted for the hug. So, a standing person should sit or kneel to hug a sitting person. A standing tall person should widen their stance or bend their knees to hug a standing shorter person, or they should find something for the shorter one to stand on.
Pressure should be firm but not suffocating- applied only from the hands and the chest, not the whole length of the arms like a boa constrictor. Imagine folding around the person like you would fold one paper around another. Pressure should also be at the top of the back and the middle of the back, because lower back is sexual for many people and so you should ask first (I certainly don't want anyone touching me there without asking).
Hand movement should be thoughtful and not too hard of a rub, nor too much in one spot, NO PATS.
Posture should be softened (if possible) with shoulders loose and spine curved: if one person stands up straight that forces the other to bend twice as much and it feels awkward and uncomfortable.