What is it?This came in as a request from a reader, and it's something I have certainly thought about quite a bit. There's actually a fair bit that can be conveyed in a handshake, maybe more than you think!
Why do it?We encounter people all the time, many of them we know and others we are meeting for the first time. How you greet them conveys a lot about who you are and what you expect out of the meeting. A handshake can also convey far more than a greeting or departure, having traditionally been used to signal agreement or to lock in a verbal contract.
How did I learn it?This is something most, if not all of us, learn as kids. There was a time that it was really only boys that learned this, but it has changed significantly over the years. Scouting introduced me to a few variations on the handshake, as did my work at Renaissance faires. Over time I've learned that some people take such things far more seriously than others, often to my chagrin.
How do you learn it?What you intend to convey will have a big impact here. There are a few basics that almost always apply:
The approach: extending the hand perpendicular to the ground but palm turned slightly upward is an inviting and friendly way to start a shake. It implies a willingness to help. It is always safe to extend a handshake to another man and to most women under the age of 45 or so. Older women may not shake hands as this is a fairly recent change in our society. Allow them to extend first. Often a mutual start of shakes will imply a fairly equal station and eagerness. When unclear, it can be fine to wait for a shake as the initiator will often appear inviting.
Of note, do not extend your left hand unless encountering someone who is obviously unable to shake with their right. This is still considered rude (barring inability) to many people.
The grip: thumb wrapped over the top, fourth and fifth fingers (depending on hand size) below. Grasp their hand firmly, though not forcefully. A soft or lame handshake is often seen as a sign of weakness or lack of interest. Too hard is rather juvenile and unappreciated. Never should your handshake cause pain.
The pump: One or 2 short pumps convey sincerity, especially when punctuating a greeting. These should follow the same rules as the grip, being somewhat firm but not overly vigorous. Don't pump too hard, fast, or often, as this belies a level of extreme excitement which may be construed as rude.
The eyes: this is a handshake, so who cares about the eyes? Everyone. Making eye contact while shaking shows you are as interested in meeting the person as they are in meeting you. It implies sincerity, trust, and an earnest nature. Failure to do so will make you appear uninterested at best and shifty at worst.
The release: Most handshakes will last 2-3 seconds, at which point both parties will release. If pressure is removed by the other party, take the signal and let go. Too long can become awkward.
Things to avoid: aside from the items mentioned above, it is worth noting a few other pitfalls. Greatest amongst them is avoiding a shake. This is considered a serious insult to the other party, implying a lack of interest or outright disdain for the presenter of the shake. If one needs to avoid a shake, perhaps for health reasons (IE, you're ill), this should be immediately vocalized with an apology. Similarly, wiping your hand AFTER a shake (it is acceptable before, especially if you have a dirty or sweaty palm) is very rude, akin to implying the other person is unclean or unworthy in some regard.
Variations: There are a number of uses for the handshake outside of greeting and farewell. When conveying concern or care, a second hand is often wrapped over the other person's hand, thus suggesting support and willingness to aid. this can often be seen at funerals and weddings. It has become popular in recent years for the handshake to be used by men of close acquaintance to initiate a hug, pulling the other person in but often maintaining the handshake. This allows a sense of physical separation while embraced.
Traditionally, a handshake has been used to conclude business and convey a sense of willingness to abide by any agreements discussed. In fact, it may be specifically asked for (IE, "Let's shake on it.") to seal a deal. Such a shake implies a willingness to take each other at your word and honor to follow through on any agreements in lieu of a contract or until one can be drawn. The breaking of such an arrangement signifies to the other party a lack of trustfulness.
What else can you tell me that may not be common knowledge?There have been a variety of handshakes over the ages, but many scholars believe it began as a method to show that a person intended no harm. As long as 2 people were gripping primary fighting hands (often the right), they could not fight. During the middle ages when the sword was normally worn on the left, holding a grip would prevent the drawing of the sword.
At some points, the forearm was clasped instead of the hand, further restricting movement, even though it brought 2 people closer into contact.
Feel free to weigh in with other thoughts below!