There are ways you can tell that you have been hacked. Unfortunately, most people are infiltrated well before they know. Some indications are:
• Unauthorized charges to your credit cards.
• Unauthorized actions in your bank or investment accounts.
• Unauthorized use of your game accounts.
• Being accused by other individuals or ISPs of sending spam e-mail you know you have not sent.
• Running a virus scanner discovers Trojans or backdoor software installed on your machine.
• Strange computer behavior, such as random reboots, sounds suddenly playing, windows popping up unexpectedly, passwords being locked out, and so forth.