What is mental slavery? What does it means to you?  How do you perceive mental slavery?

I was just thinking could it be accurate to conclude that even though slavery is been over (to some fashion), but somehow mental slavery still exist in some?  So, I Google what is mental slavery?  I come across different opinioned answers but the one that stroke me the most is this one “Mental Slavery is when your under the impression that reality is one thing when its another and your mind is being influenced to work to benefit a group of people.”

I find it very interesting and ironic!