Using the right hand is generally considered proper etiquette. Customs surrounding handshakes are specific to cultures. Different cultures may be more or less likely to shake hands, or there may be different customs about how or when to shake hands.
Archaeological ruins and ancient texts show that handshaking – also known as dexiosis – was practiced in ancient Greece as far back as the 5th century BC; a depiction of two soldiers shaking hands can be found on part of a 5th-century BC funerary stele on display in the Pergamon Museum, Berlin (stele SK1708) and other funerary steles like the one of the 4th century BC which depicts Thraseas and his wife Euandria handshaking. The handshake is believed by some to have originated as a gesture of peace by demonstrating that the hand holds no weapon, back in the caveman days. However, the Romans who liked to hide daggers in the arms of their robes, used to grab each other's sleeves when they met, to figure out the other's intentions. Meanwhile, Muslim scholars tell that custom of handshaking was introduced by the people of Yemen.
There are various customs surrounding handshakes, both generically and specific to certain cultures:
The handshake is commonly done upon meeting, greeting, parting, offering congratulations, expressing gratitude, or as a public sign of completing a business or diplomatic agreement. In sports or other competitive activities, it is also done as a sign of good sportsmanship. Its purpose is to convey trust, respect, balance, and equality. If it is done to form an agreement, the agreement is not official until the hands are parted.
Unless health issues or local customs dictate otherwise, a handshake is made usually with bare hands. However, it depends on the situation.
In Anglophone countries, handshaking is common in business situations. In casual non-business situations, men are more likely to shake hands than women.
Austrians shake hands when meeting, often including with children.
In the United States a traditional handshake is firm, executed with the right hand, with good posture and eye contact.
In Russia, a handshake is performed by men and rarely performed by women.
In some countries such as Turkey or the Arabic-speaking Middle East, handshakes are not as firm as in the West. Consequently, a grip that is too firm is rude. Hand shaking between men and women is not encouraged in the Arabic world. Also, only the right hand should be used.
Moroccans also give one kiss on each cheek (to corresponding genders) together with the handshake. Also, in some countries, a variation exists where instead of kisses, and the handshake the palm is then placed on the heart.[clarification needed]
In China, Age matters here, so greet the oldest people first. A weak handshake is also preferred, but people shaking hands often hold on to each other's hands for an extended period after the initial handshake.
In Japan, it is appropriate to let the Japanese initiate the handshake, and a weak handshake is preferred. The Japanese do not have a tradition of shaking hands and prefer to formally bow (with hands open by their sides) to each other, but they will greet non-Japanese with a handshake.
In India and several nearby countries, the respectful Namaste gesture, sometimes combined with a slight bow, is traditionally used in place of handshakes. However, handshakes are preferred in business and other formal settings.
In Norway, where a firm handshake is preferred, people will most often shake hands when agreeing on deals, in private and business relations.
In Korea, a senior person will initiate a handshake, which it is preferred to be weak. It is a sign of respect to grasp the right arm with the left hand when shaking hands. It is also disrespectful to have your free hand in your pocket while shaking hands. It is considered disrespectful to put one's hand in your pocket while shaking another person's hand. Bowing is the preferred and conventional way of greeting a person in Korea.
Related to a handshake but more casual, some people prefer a fist bump. Typically the fist bump is done with a clenched hand. Only the knuckles of the hand are typically touched to the knuckles of the other person's hand. Like a handshake the fist bump may be used to acknowledge a relationship with another person. However, unlike the formality of a handshake, the fist bump is typically not used to seal a business deal or in formal business settings.
The hand hug is a type of handshake popular with politicians, as it can present them as being warm, friendly, trustworthy and honest. This type of handshake involves covering the clenched hands with the remaining free hand, creating a sort of "cocoon".
Another version popular with politicians is a "photo-op handshake" in which, after the initial grasp both individuals turn to face present photographers and camera men and stay this way for several seconds.
In some areas of Africa, handshakes are continually held to show that the conversation is between the two talking. If they are not shaking hands, others are permitted to enter the conversation.
Masai men in Africa greet one another by a subtle touch of palms of their hands for a very brief moment of time.
In Liberia, the snap handshake is customary in which the two shakers snap their fingers against each other at the conclusion of the handshake.
In Ethiopia, it is considered rude to use the left hand during a handshake. While greeting the elderly or a person in authority, it is also customary to accompany the handshake with a bow and the left hand supporting the right. This is especially important if it is the first time.
In Thailand, handshaking is only done if the traditional "Wai" is not offered. The person will offer what’s called a “wai,” placing their palms together at chest level and bowing. Return the gesture. If you’re a man, greet then with “Sawadee-krap.” If you’re a woman, say “Sawadee-kah” (both mean “Hello). 
Handshakes are known to spread a number of microbial pathogens. Certain diseases such as scabies are known to spread the most through direct skin-to-skin contact. A medical study has found that fist bumps and high fives spread fewer germs than handshakes.
Following a 2010 study that showed that only about 40% of doctors and other health care providers complied with hand hygiene rules in hospitals, Mark Sklansky, a doctor at UCLA hospital, decided to test "a handshake-free zone" as a method for limiting the spread of germs and reducing the transmission of disease. However, UCLA did not allow the ban of the handshakes outright, but they rather suggested other options like fist bumping, smiling, bowing, waving, and non-contact Namaste gestures.
It has been discovered as a part of a research in the Weizmann Institute, that human handshakes serve as a means of transferring social chemical signals between the shakers.
It appears that there is a tendency to bring the shaken hands to the vicinity of the nose and smell them. They may serve an evolutionary need to learn about the person whose hand was shaken, replacing a more overt sniffing behavior, as is common among animals and in certain human cultures (such as Tuvalu, Greenland or rural Mongolia, where a quick sniff is part of the traditional greeting ritual).
In 1963, Lance Dowson shook 12,500 individuals' hands in 101⁄2 hours, in Wrexham, N. Wales.
Atlantic City, New Jersey MayorJoseph Lazarow was recognized by the Guinness Book of World Records for a July 1977 publicity stunt, in which the mayor shook more than 11,000 hands in a single day, breaking the record previously held by President Theodore Roosevelt, who had set the record with 8,510 handshakes at a White House reception on 1 January 1907. Dowson's record was recognised by the Guinness World Records Organisation and published in their 1964 publication. WSAI DJ Jim Scott broke the record at Northgate Mall, Cincinnati, Ohio. On 31 August 1987 Stephen Potter from St Albans Round table shook 19,550 hands at the St Albans Carnival to take the world record for shaking most hands verified by the Guinness Book of World Records. The record has since been exceeded but has been retired from the book. Stephen Potter still holds the British and European record.
On August 15, 2008 Kirk Williamson and Richard McCulley broke the Guinness World Record for the World's Longest Handshake (single hand) when they met at Aloha Stadium in Honolulu, Hawaii and shook hands for 10 hours, besting the previous record of 9 hours and 19 minutes set in 2006. On 21 September 2009, Jack Tsonis and Lindsay Morrison then broke that record by shaking hands for 12 hours, 34 minutes and 56 seconds. Their record was broken less than a month later in Claremont, California, when John-Clark Levin and George Posner shook hands for 15 hours, 15 minutes, and 15 seconds. The next month, on 21 November, Matthew Rosen and Joe Ackerman surpassed this feat, with a new world record time of 15 hours, 30 minutes and 45 seconds certified in the latest edition of the Guinness Book of Records[which?] on page 111. At 8 p.m. EST on Friday 14 January 2011 the latest attempt at the longest hand-shake commenced in New York Times Square and the existing record was smashed by semi-professional world record-breaker Alastair Galpin and Don Purdon from New Zealand and Nepalese brothers Rohit and Santosh Timilsina who agreed to share the new record after 33 hours and 3 minutes.
In June 2016, an Algerian woman married to a Frenchman took part in a naturalization ceremony (cérémonie d’accueil dans la citoyenneté française) in the Département where the couple lives. She refused to give a handshake to the prefect and to a local representative and claimed her religious faith would ban her from touching foreign men. Thereupon, she did not receive the French nationality. On 20 April 2017, Prime MinisterBernard Cazeneuve signed a decree approving that decision. The Algerian woman filed a suit. On 11 April 2018, the Conseil d'État approved the decree.
^Busterson, Philip A. Social Rituals of the British.
^"Dear Uncle Ezra – Questions for Tuesday, April 3, 2007". Cornell University. 3 April 2007. Question 8. Archived from the original on 26 September 2011. Retrieved 4 September 2011. There are many conflicting theories about the origin of the handshake. It seems that the most common one involves the evidence of the lack of a weapon in the right hand, which normally bears a weapon. It is shown to be empty by its connectedness to the opposite person's hand.[full citation needed]