World Mental Health Day was created by the World Health Organisation (WHO) to raise public awareness of mental health issues.
It's thought that around 154 million people around the world suffer from depression, so it's likely that you or someone you know will be affected by mental illness during your lifetime.
World Mental Health Day aims to get us all talking openly about mental illnesses and the treatment and preventions that are available to us all.
The day will be organised with the help of the World Federation for Mental Health which was founded in 1948 to prevent emotional and mental health disorders and help those who do suffer from them.
This year the theme is "Mental health and older adults" and you can show your support by making a donation at the World Federation for Mental Health website, or by joining in with one of the events organised for the day.
Events include community workshops with talks from professionals to give you any advice you might need.  
To find out more and to get involved, visit the World Mental Health Day official website and don't be afraid to talk about your problems this World Mental Health Day.