Types of viruses.

Virus: A virus is a program code that penetrates the computer system and infects files on the computer. The main task of a virus is to harm the operating system. Infection occurs mainly when visiting malicious sites, downloading files from dubious resources, opening letters from unknown senders.

1. Worm: worm does not infect user files. Penetrating into the system, they begin to multiply uncontrollable, looking for vulnerabilities in the network in order to spread further. The vital activity of computer worms a lot of computer system resources.
2. Trojan: trojan this infection is usually embedded in peaceful or hacked programs that are distributed free of charge. The main task of the Trojan is to steal confidential user data or install malicious code.
3. Ransomware: ransomware is distributed by cybercriminals on the Internet in the form of complex cryptographic algorithms, with the aim of encrypting files on users’ computers, with subsequent demand for ransom for decrypting them. This class of malware is a criminal moneymaking scheme that can be installed through deceptive links in an email message, instant message or website.
4. Hacktool: penetrating the computer, this malware adds new users who are allowed to use the operating system, and also deletes or hides system logs, hides traces of intruders in the system.
5. Adware: Adware is software which can automatically cause pop-up and banner adverts to be displayed in order to generate revenue for its author or publisher. A lot of freeware uses Adware but not always in a malicious way. If it was malicious, it would then be classed as spyware or malware.