Depression is when people feel sad, upset or down all the time and they don't know why. It's like having a dark cloud over your head that follows you around wherever you go. People with depression often lose interest in things they used to love and might find it hard to keep up with their daily routine.
Sometimes, depression can come out of nowhere, even if everything is going well in a person's life. Other times, it can be caused by big changes like moving to a new house or school, having problems with friends, or losing someone they love.
Depression is not something that people can just "snap out of" or "toughen up" to overcome. It's important for people with depression to get help from a doctor, counselor, or therapist, who can help them feel better. They might also need medicine called antidepressants that can balance the chemicals in their brain and help them feel happier.
It's important to remember that people with depression are still important and loved, and that getting help is a brave thing to do.