How Do You Know If You've Been Hacked?

 In response to Joshy1028's request. This is a very good and important question. Unfortunately, it's not always an easy answer.. I only know of a few ways that are hints that you might have been hacked. If any of these cases are true for you, don't panic. This usually makes things get worse. Most of these are easy to correct.

•      Unapproved User On Your Computer

 Sometimes, hackers will get into your computer and create a new user. Creating a new account, for their use, allows them better access to your computers resources, without your knowledge. A quick check, listed below, will tell you how to check for this.

1. Log into your computer as an Administrator. (Most of the time if there's only one account on the computer, you are already the administrator. Depends on what version of Windows you're using)
2. Click "Start", then type "Run" into the search box. Click the "Run" link that appears. After the Run box pops up type in "CMD". This will open your command prompt screen. 
3. In the new command prompt window, type "net user" and press "enter". Windows will now display all users that have been created on your computer. 
4. After you run the "net user" command, there will be a small list of  users that are on your computer. If there is a user on there that you are not aware of, it's likely a hacker. Remove the user at once. 

• Check To See If You Passwords Have Been Compromised.

 A good place to start is here. Enter your E-mail, click "Check it", and it will search stored databases for your e-mail and try to find if there is a password stored with said e-mail. The website doesn't log your e-mail. If it brings up that it's found your password, CHANGE YOUR PASSWORD. This means that your password is in a database that hundreds of people have access to.

• Other Slight Changes That Are Good Indications Of Being Hacked.

1.  You end up finding personal information on the Internet, that did not come from you. This could be phone number, address, last name, and any other personal information that people might not put on the Internet.
2. You find weird and/or random programs on your computer that you did not install yourself. Computers come pre-loaded with hundreds of programs and files already installed. What you have to worry about is the creation date. Programs that were installed within the last week or so, that you have no knowledge of. These are more than likely placed by hackers.
3. You are constantly using Bandwidth, even when you are not using your internet. A hacker that has entered your network, whether through hacking, or entering through an unsecured network, will be using your Internet connection. Most of the time, you can view whether or not Bandwidth is being used simply by looking at your router/modem. Be aware, however, that any computer connected to the network will cause the blinking lights telling you that your network is being used. 
4. The contents of files change. This is something you might not even notice. If you happen to go into a Word or Notepad file, and you notice the contents went from something like "My History Project" to a bunch of random characters, something is wrong. Delete the file at once and try to scan with an anti-virus to see if any damage was done.
5. Passwords change. If you go to sign into your computer, your e-mail, or another random website in which you have an account, and you think your password has been changed, that's another good indication that someone has been there, and messing with your accounts. Use an "I forgot my password" link and change it to something harder to figure out, and possibly let the company (I.E. Hotmail for hotmail.com) know that you believe your account has been hacked. Sometimes they can do something for you.
6. If you have a Firewall installed, sometimes you will get a notification. Most of the time the notification will alert you there's been an attempt, and will prevent the intrusion. A Firewall is a very good thing to have installed.
7. If you notice a dramatic increase or decrease in your Disk Space on your Hard Drive, that you did not do, you may have had a hacker in your computer. A lot of times, if hackers are there to mess with you, they will delete several files, or install several files. This will cause a huge difference in the amount of storage space you had before and after. Going from 103 G Free Space to 99 G Free, for instance, is a bad sign.

These are just a few signs that your computer has been compromised. Please take action if you fit these cases. And as always, do what you can do to prevent Hackers as much as you can!