During his long and storied career in tennis, Rafael Nadal was famous for many things.

The power and precision of his top-spin backhand. His dogged determination to chase down every ball. Those bulging biceps.

If you ever saw Nadal in action, you know he is also a staunch ritualist. Before every match, the Spanish legend performed 19 separate rituals.

The most visible was an elaborate dance of self-touching. Nadal tapped the back and front of his shorts with his right hand. Then, with the same hand, he touched his left shoulder, then his right shoulder, then his nose, left ear, then his nose again and then his right ear. He finished by touching his right thigh. He thought about each tap and always carried them out in exactly the same sequence.

To the rest of us, this court-side kabuki looked like pointless superstition. But the opposite is true: performing those 19 rituals made Nadal a better tennis player. "If my rituals were superstitious why would I keep doing the same thing over and over whether I win or lose?," he said. "My rituals are a way of placing myself in a match, ordering my surroundings to match the order I seek in my head."

And it worked: before retiring last year, Nadal won 22 Grand Slam titles.

Nadal is not alone. In every walk of life, we use rituals to order our surroundings and create order inside our heads. We always have. Rituals are, in the words of anthropologist Roy Rappaport, "humanity's basic act".

Rituals are also found across the animal kingdom. Magpies, ravens and crows flock over the bodies of their dead, arranging sticks and other objects around them. Dolphins perform group dances. Elephants stay with their dead for days on end, covering them with leaves and flowers, and returning to the bones years later.

The more intelligent the animal, the more rituals they tend to perform. Our nearest relatives, chimpanzees, carry out special dances beside waterfalls that last up to 15 minutes. When meeting up again after being apart they perform a series of handshakes, hugs and kisses. Chimpanzees have even been observed placing stones by specific trees and then treating them like points of pilgrimage.

No animal, however, is as ritualistic as humans. Our oldest known ritual dates back 70,000 years to a cave in Botswana, where archaeologists found evidence of humans using spearheads as sacrificial offerings to a stone python. Early homo sapiens had elaborate burial rituals, adorning the bodies of their dead with everything from jewellery to art. Most traditional societies created rituals for burning, burying or eating the placenta.

Even today, we remain hardwired for ritual. From the age of two, children start developing their own rituals – kissing a favourite toy the same way every morning, for instance, or listening to the same bedtime story every night. When shown someone performing a task in a ritualised manner, three- year-olds will faithfully copy every step, including those that are clearly irrelevant to completing the task.

Adults instinctively believe in the power of rituals. This is true even when those performing them are total strangers in an unfamiliar context. One example: when people with no knowledge of basketball were asked to watch players shooting free throws, they assumed that those with pre-shot rituals would be 30% more successful.

“We are an intensely ritualistic species,” says research psychologist Nick Hobson. “Take rituals out of our narrative and you lose a piece of our history and our humanity."

We need rituals now more than ever. Thanks to climate change, culture wars, economic stagnation, real wars and the rise of artificial intelligence, this is a time of roiling upheaval – and rituals are a powerful tool for thriving in the storm. Until recently, that was impossible to prove because we did not have the technology to analyse how rituals work. Now we do.

Thanks to advances in wearable sensors, data analysis, the cognitive sciences and brain imaging, we are putting the human penchant for ritual under the microscope like never before. And we're discovering that rituals can:

1. Curb performance anxiety

2. Deepen relationships

3. Build identity

4. Foster a sense of belonging

5. Help us deal with loss and grief

6. Increase feelings of control

7. Intensify the pleasure we take from from food, sex and everything in between

8. Boost teamwork

9. Increase productivity

10. Increase trust

11. Deepen our connection to the past

12. Build stronger memories

13. Give shape and meaning to life

14. Provide escape and transcendence

15. Reduce stress and anxiety

16. Sharpen mathematical performance

17. Bind groups and societies together

18. Make us more generous and altruistic

19. Boost self-confidence

20. Deliver a sense of achievement and growth

The message from science is clear: Rituals are a universal tool we can all use to become better people leading better lives in a better world.

Let's now define our terms:

A ritual can be religious or secular. Think holy Communion in the Catholic Church versus a hog roast in the Deep South. Some rituals are public, such as the changing of the Queen's Guard outside Buckingham Palace. But most rituals are private. No family does Sunday lunch or Games Night exactly like your family. Every couple has its own secret phrases, gestures and nicknames, its own sexual script.

That means we can invent rituals – anytime, anywhere.

Three centuries ago, Benjamin Franklin came up with a ritual that he dubbed the 'air bath': "I rise early almost every morning, and sit in my chamber without any clothes whatever, half an hour or an hour, according to the seasons, either reading or writing."

Across the world, we created new rituals to cope with the pandemic. Many of us stood on our doorsteps every week to clap and show our support for essential workers. Parents in the United States drove past the homes of their children's schoolteachers, tooting their horns and waving in gratitude. Locked-down residents in the Italian town of Bella devised an evening ritual to socialise in a time of social distancing. By fixing cup holders on the end of long bamboo sticks they were able to clink wine glasses with neighbours across the street.

Jimmy Kimmel, the US comedian, devised a ritual called Formal Fridays: trapped in quarantine, he and his wife would dress up to the nines for dinner at home once a week.

Sometimes rituals emerge almost by accident. It can start when, on a whim, you add a twist to an otherwise ordinary act. Perhaps, while making a cup of tea, you decide to stand on one leg until the water boils in the kettle. You enjoy the new flourish, and start doing it regularly. After a while you can no longer imagine making a cup of tea without standing on one leg. Presto, you've created your own ritual.

Like many people, I started taking long walks during the pandemic. The route was a six-mile loop from my home in London. It snaked down streets lined with Victorian terraces, past shops, restaurants and schools, across three commons. Every evening, I followed the same path – and never tired of it. On the contrary, the repetition and familiarity were part of the charm. I looked forward to my evening stroll. It was a time to escape, reflect, recharge, something to look forward to when the days felt long and bleak. The walk marked the end of my working day, delivering me home refreshed and rebooted. I even gave the six-mile stroll a name: The Three-Commons Walk.

When lockdown ended, I no longer had the time or the inclination to spend every evening marching round south London. But the Walk remains part of my life. I still do it once a week.

Through months of repetition, the Walk stopped being just a walk and became a ritual.

Repetition is also a feature of habits and routines. But rituals differ in key ways. To begin with, routines and habits can be performed on auto-pilot. You can fold the laundry, brush your teeth or shoulder-check when changing lanes without thinking about it.

Rituals cannot be performed on auto-pilot. They demand intention and attention. A ritual must be performed mindfully. And often slowly.

Rituals must also be enacted in exactly the same way each time. Routines and habits can vary from day to day. You don't always brush your teeth or fold the laundry in precisely the same way. And that's okay.

Not so with rituals. Failure to perform a ritual exactly as prescribed can drain the act of its power and meaning, and provoke consternation and outrage among those who hold that ritual dear.

Taking the presidential oath in front of the U.S. Capitol building in Washington D.C. is one of the great set-piece rituals in American life. When Barack Obama joined the club in 2009, he mangled some of the words. To non-Americans, his slip up was trifling, no more than a footnote to an historic moment. To many of his fellow citizens, however, it was an alarming breach. Some felt it undermined the legitimacy of his presidency. To silence the doubters, Obama retook the oath at the White House with members of the press as witnesses. The second time he made sure to get all the words right, allowing the nation to breathe a sigh of relief and move on.

Routines and habits are also designed to deliver a specific result: brushing your teeth improves your dental health; shoulder-checking makes you a safer driver; folding laundry keeps your wardrobe in order.

The same goes for superstition. People stab voodoo dolls in the belief that the person depicted by the doll will come to harm. Follow the recipe and (in theory, at least) you get the desired result.

By contrast, rituals lack what scholars call "direct instrumental purpose". That means they are not designed to achieve a specific goal. What matters is not the direct effect a ritual will have on you or the world. It may have no effect at all. After all, a rain dance does not make it rain.

What matters is the act of taking part in the ritual. What matters is the ritual itself.

When a tennis player stretches before a game, that is a habit or a routine. Limbering up helps her hit better shots and avoid injury. When Serena Williams bounces the ball exactly five times before her first serve and two before her second serve, or wears the same socks and uses the same shower and ties her shoelaces the same way throughout a tournament, that is ritual.

To everyone else, Williams’ rituals, like Nadal's, look like a quirky waste of time. Copying them would do nothing for the rest of us. It would not supercharge our serve, burnish our ground strokes or turn us into Grand Slam winners.

Yet Nadal and Williams cannot conceive of playing without their rituals. Williams has even blamed tournament losses on her failure to enact them. "The utility of the ritual isn’t related to its practicality," says Mike Norton, an expert in rituals at Harvard Business School. "Even the most absurd ritual can have high utility."

Rituals can date back a thousand years or a month. You can perform them with others or alone. They can appear noble and profound or weird and silly. Their form does not matter. Which means every one of us can tap the power of ritual.

Of course, rituals are not always a force for good. Cults use them to fire up and control their followers. Dictators do the same: remember the Nuremberg Rallies.

It is also possible to lean too heavily on rituals. You might start off using one to feel more in control over your life but what happens if the ritual takes control of you? People with obsessive-compulsive disorder (OCD) can end up with elaborate rituals that make it hard to lead a normal life, such as having to wash their hands in exactly the same way 20 times every hour.

Rituals also have a PR problem.

During the Enlightenment, which put rationality and science on a pedestal, they came to be seen as backward and obscurantist, as a form of empty conformity. Even today, we talk of "ritual abuse" and "ritual sacrifice". The very word "ritualism" hints at deviance or excess.

Rituals are also at odds with the modern obsession with metrics, efficiency and outcomes. By defying easy measurement and failing to tell a simple cause-and-effect story, rituals can look indulgent, inefficient, even pointless.

If wearing the same socks all the way through a tennis tournament has no direct, measurable effect on how well human beings play, why not just change your socks?

Rituals are not the solution to every problem. But they can be a formidable tool. When used wisely, rituals can bring us together and unleash our full potential.

What are your favourite rituals?