When we publish content on Internet, we have to be aware of what is permitted and what is illegal. There are several points to take care of :
Internet and social media are like public spaces and you can not do whatever you want just because you feel it. No one is used to go naked on the streets and to insult his/her neighbour just because she/he doesn't agree with her/him.
What's more, laws concerning privacy and copyright are very different from one country to another. For instance, the german law is very severe about author's rights and data protection whereas the american law is much more concerned with business protection through copyright and user's contract.
To support a responsible use of Internet publishing, you have always to follow a very simple rule :
« Think before you post ».