What is the differents between sadness and depression?

Sadness is just an emotion we all feel at some point of our lives, we can be happy on a moment and sad the moment after, and this is not to worry, since being sad is part of the human condition.
Depression is a serious medical illness that has to be treated with pills and psychological help, and it can take several months or years to pass.

Sadness is temporary and depression lasts and depression is a mental illness sadness is not

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