Privacy

Privacy is the ability to choose what information is hidden and who it's hidden from.
Privacy laws in many countries give the right not to be unfairly subjected to invasions of privacy. 
The Universal Declaration of Human Rights says that privacy is a human right.
Importance.
Everyone wants to keep things about them private.
Some people want to keep their religion, sexual orientation, and opinions private so that they don't get in trouble with their government, the people they know, or both.
Internet privacy.
Many things on the internet are tracked and sometimes sold by different groups of people. 
For example:
The senders of an email can track the time you open an email using pictures that sometimes can't even be seen.