Increasingly, studies by psychologists show how serious the influence of friends in our lives is.
Numerous studies have shown that friendship can be good for our health.
How romantic relationships affect our health has been known for a long time. A study reported by Medical News Today last year, for example, suggested that one spouse is 40-70% more likely to start exercising if the other spouse does so, while another found that healthy lifestyle changes are more successful if implemented with partners.
But perhaps less well known are the far-reaching health benefits associated with friendship, defined in simple terms as mutual attachment between two or more individuals.
It may not be surprising that friends have a good influence on us, especially when it comes to mental health; most of us have probably gone through some bad times during which our friends were there to offer emotional support and help get us out of depression.
In fact, scientists have proven that people with good friendly support have a much lower risk of depression. One study published last year showed that contact with friends at least three times a week almost halves the risk of depression for older people.
But the health benefits of friendship go much further, as do the health risks associated with a lack of companionship.
The focus of the researchers is on the various ways in which friendship has a positive impact on us and allows us to look at why our friends play such an important role in our health and well-being.
One of the most obvious benefits of friendship, reducing stress, should not be overlooked.
According to the American Institute of Stress, about 3 out of 4 visits to doctors are the result of stress-related diseases, and stress is the main cause of 60% of all human illnesses and diseases.
However, in 2011, a study published in the Journal of Psychology of Development was conducted. It suggests that simply being close to a good friend during a negative experience can reduce stress.
The study, which involved 103 children aged 10-12 years, showed that children who spent time with their best friend during a negative emotional experience had lower levels of cortisol stress hormone in their saliva than those who had a negative experience with a parent, brother, sister, teacher or other person.
And a new study by scientists at the University of California, Berkeley, recently published in the journal Neuropsychopharmacology, suggests that male members of the male community who have experienced stress together can cause friendship.
To reach their conclusions, the lead author of the study, Elizabeth Kirby of the Department of Integrative Biology at the University of California, Berkeley, and her colleagues placed rat males in the same cell.
As a rule, male rats in this situation showed aggression against each other. However, the researchers found that exposing rodents to moderate stressors - 3 hours of acute immobilization - they actually made them become friends.
Compared to male rats that were placed together in a stress-free environment, those that were exposed to moderate stressors showed an increase in levels in the brain of oxytocin - known as the "love hormone" - and were more fond of each other when they saw an old friend, heard a song that reminds you of your past, and received good news from your loved one and you are happy. We have made a new list of 50 simple things that are likely to leave a smile on your face. A survey of 2,000 adults published on World Smile Day showed that despite the uncertain times, most Britons consider themselves to be "half-filled with glasses" - a person who lives happily for half a week.
Eating comfortable food, sleeping in a fresh bed, finding dozens in an old pair of jeans and watching funny videos online have completed the top 10 list of 50 simple reasons to smile.
The same smile is used by children who have received a good mark at school, parents who have heard the first word of their child, or a simple kiss on the cheek - doing the same miracles.
From funny animals to missed parties, you can find a smile by watching a selection of funny video playlists on YouTube.
"As the old saying goes, a person needs less muscle to smile than a frown. So we tell nations to take on the challenge of smiling, sharing their experiences, telling them what makes people smile.
Analysts say that funny dances and animals cause the most smiles, and then TV lapses and sports events.