When we show kindness to others, we make a deliberate choice to do something that's intended to benefit another or make them feel better.
By doing so, we make ourselves happier and healthier, as well.
Some kind acts take effort, such as volunteering, running errands for people in need, cleaning up a nature area, giving blood or organising celebrations for 'unsung heroes'.
Other acts of kindness are smaller, such as giving compliments, sending a card to someone who needs cheering up or connecting with someone who's feeling isolated.
While kindness is about helping others, studies have found that people who act kindly enjoy benefits themselves: higher levels of happiness and life satisfaction, less social anxiety and greater social acceptance.
Kindness can also become contagious, spreading through networks and communities.
During this tough year when we've had to stay apart, it's been inspiring to see people using technology and public spaces to spread kindness.
Some people have used their social media to share good news stories or messages of gratitude and hope, while others have decorated their houses and streets to cheer up others.
Now, as we're gathering together again, let's reflect on what we've learned about kindness this year, and how we can use those lessons moving forward.