International Friendship Day is a celebration to mark friendships from all over the globe. Celebrated on the second Sunday in August every year, its purpose is a day to reflect on the friendships that are important to us as individuals, whether they be with an old school friend, a sibling, a colleague or even a pet.

Friendship is an integral part of our lives and our happiness. Friends come in all shapes and sizes and offer different things. Some friendships are forged in childhood, when individuals often make lifelong friends. These friends can be turned to in times of crisis and celebration, such as the death of a loved one or a happy occasion such as a wedding. Others are cemented at college and university when people traditionally begin to widen their social circle and incorporate friendships through shared interests. We rely on friends as well as family for support, companionship and advice at various stages of our lives.

Friendship day was originally conceived by the greeting-card company Hallmark in 1919 as a day for friends to exchange cards. By 1940 the celebration had all but died out but has been revived in recent years, particularly in Asian countries such as Singapore and in Australia. In April 2011, meanwhile, the United Nations declared July 30 as International Day of Friendship, a separate event designed to "strengthen amity between peoples and cultures".

When it was conceived in 1919, International Friendship Day was designed as an occasion for friends to send each other cards. In 2011, and considering the global nature of friendship, sending an email or a Facebook message is just as convenient and thoughtful. Many choose to pick up the phone and tell someone just how much their friendship means, send flowers to a friend who needs a boost, or give friends who are close by a hug.

Friendship can lead to a longer and happier life. A 2004 Australian study conducted over a 10-year period concluded that among older people, those with large groups of friends were 22 percent less likely to die before those with a smaller group of friends. In 2008, a Harvard study found that strong friendships had a positive effect on brain health as we age. As well as practical benefits, fulfilling friendships have a positive impact on our psychological well-being.