One of the most common threats to internet security is the presence of hackers. The term hackers refers to people who use their usually advanced computer skills for malicious or criminal purposes, which usually involve breaking (or hacking) into computers of unsuspecting users and exploiting the user's information.

Hackers are notorious for using their skills to launch attacks not only on home computer users, but also on companies, corporations, and even government security systems.

Hackers are motivated by different aspects of the results they get compromising computers. Some hackers earn a living by tampering with the security of computers, stealing passwords and personal information, or using computers as zombies to remotely control the computers for the hackers purposes. Some hackers vandalize high-profile computers to make a statement, and still other hackers hack for the thrill of being able to breach the security systems of guarded computers without getting caught.

Some hackers, regardless of specific motivation, enjoy compromising computer security without permission. However, not all hackers are cyber criminals; in the world of elite computer programmers, the word hackers can be used to refer to programmers themselves or people that modify technology hardware, which are considered generally positive definitions. When cyber crime started to become widespread, the mass media popularized the word hackers, using it to refer to cyber criminals, and the negative definition stuck.

The motivations of hackers (or crackers, as they call themselves) may vary, but installing a built-in, hardware, or third-party firewall increases your security and keeps hackers from breaking into your computer. If your computer's security has been breached, there are several steps you need to take:

1. Disconnect your computer from the internet.
2. Install a firewall to guard against future attacks
3. Run updated anti-virus and anti-spyware scans to check for unauthorized programs, changes, and installations. In the event you find them, remove them from the hard drive.
4. Wipe your hard drive and reinstall everything. This is often the only way to remove all the damage from your system.

Since it can be difficult to tell if hackers have invaded your system, the only way to have complete peace of mind is to start fresh. Some signs that your computer has been attacked by hackers include:

1. The appearance of unfamiliar data, files, or programs on your computer.
2. Spam sent from your computer's email system, the result of added software.
3. Garbage data sent to other computers from yours. Hackers could be using the computer as a zombie to attack other computers in a distributed denial of service (DDoS) attack.
4. Unauthorized disappearance of money from your bank account. Hackers with access to your computers could monitor any computer-based banking you do, including storing account numbers, passwords, and user Ids on your hard drive.

Hackers present a threat your security, but they are not infallible and can be blocked or have their access removed from your computer. Taking the necessary steps to prevent hackers from accessing your system can help keep you and your computers safe.