Nowadays hand-holding has attracted the interest of scientists who are studying its effects on the body and mind. And sexual health educators say it is a much-discussed topic among gay students who now publicly hold hands more than ever before but still must consider whether they want to declare their sexuality.

“I think it remains more important in an era of perhaps more liberal sexual norms,” Dr. Conley said. “It remains this thing to be doled out.”

To hold someone’s hand is to offer them affection, protection or comfort. It is a way to communicate that you are off the market. Practically speaking, it is an efficient way to squeeze through a crowd without losing your partner. People do it during vigils, marches, weddings and funerals.

Usually it connotes something innocuous and sweet about a couple and their relationship. In rare instances, it takes on added potency, such as when President George W. Bush held the hand of Crown Prince Abdullah of Saudi Arabia in Crawford, Tex., last year — an act of respect and affection in Arab countries — reminding some people of the film “Fahrenheit 9/11,” which depicted the Bush family’s close business ties to Saudi leaders and which ignited conspiracy theories.

But, over all, few things are more innocent than a child grabbing the hand of a parent, for protection, direction and, as Mr. Findlay put it, connection. And with many children these days closer and more outwardly affectionate to their parents, chances are you have spotted a mother and her teenage daughter and perhaps even a father and his adolescent son ambling through a mall, scurrying through a crosswalk or strolling along, hand in hand.