Society or the state of the world; often refers to public mores or social conditions.
世の中は日々変わっていく。
The world/society changes day by day.
世の中の常識が通用しない場合もある。
Sometimes common sense of society does not apply.
世の中の流れを知るために新聞を読む。
I read the newspaper to keep up with what's happening in society.
世の中には優しい人も多い。
There are many kind people in the world.