Keylogger is a generic name for a program that is able to record all keystrokes. There are specialized keylogging programs, but also there are different viruses made to steal personal information. Often, these programs aren't visible on desktop, start menu or other locations and are not detected by regular anti virus software.
Keyloggers are programs designed for parents to monitor their children and for employers to monitor their employees, but can be used illegally to spy on you.
Keyloggers can record and save locally or send remotely different data: usernames and passwords, visited websites, screen capture at regular intervals, can record audio (microphone), copied text (clipboard), online discussions and more.
Anti-keyloggers are specialized programs made to detect and block the keyloggers. Keep in mind that the keyloggers can have innocent names after installation, so you should expect that your anti-keylogger software will alert and block file names that make no sense.
Keyloggers are made to steal any kind of data. They can record usernames and passwords of your e-mail, e-banking accounts, information typed when you make online payment (credit card number, CCV, email, address, phone number).
Antivirus programs doesn't offer a strong protection and detection against keyloggers. We tested best keyloggers and one of the best and popular antivirus programs was able to detect just a few of them (read about best keyloggers and monitoring software on this page).
Is obviously that having an anti-keylogger software it makes perfect sense.
What about free anti keyloggers? You will not find a complete free anti-keylogger to detect and block all threats, but most of commercial programs include a period of full trial, so you can pick one and make a full scan on your PC.
We tested each anti-keylogger against top 5 keyloggers, one by one. We tested against high quality keyloggers (paid ones) made to monitor children and employees, but they can be used by others for illegal purposes such as stealing your data.
The best keylogger detectors provide a high detection ratio for programs or viruses that try to record data.
Detection If you already have installed a stealth keylogger, these programs will be able to detect it immediately. Also, if you install by mistake a virus (a RAT - remote access trojan) which attempt to record data or take control of your webcam, the keylogger detector will spot and block it instantly.
Protection Is not enough to protect you against keystroke loggers. Keyloggers can record, steal and send remotely screen captures of your entire screen at different intervals, can take screenshots of your webcam and even to record your microphone. A good anti-logger will detect any of these suspicious activities and will alert you.
Program Features Some keyloggers can disable your antispyware protection. Is good that the access to anti-keylogger's settings to be protected with a password or Captcha code. The keystroke encryption is also useful because if the anti-keylogger will not detect a new malware, all keys typed will be randomized or replaced with other keys for these keyloggers, so they will not record exactly what you typed.
Also, you should see what items have been blocked or allowed because someone may have access to your computer, install a keylogger in stealth mode, then click Allow/Trust when the anti-keylogger detects it.