He follows you down the street. Trailing behind, you don't know he is there. He takes pictures of you going in and out of your house, and your workplace. He uses easy to buy and use software on the internet to look up all your records.

He uses spyware to track you on the Internet.

He uses a high end microphone to listen in on your conversations.

He is a stalker.

But, if he takes some classes and gets a license, he is called a Private Investigator.

Perception and name are everything aren't they?