Viruses and other types of malware
Malware is malicious software that can sneak onto your phone. Written with the intent to cause harm, malware can include viruses, computer worms, Trojans, ransomware, and spyware.
Cybercriminals can use malware to access your personal data and, in some cases, subsequently use that sensitive information to commit identity theft or fraud.
Viruses are a particular type of malware that infiltrate a computer or other device and their programs. A cybercriminal may be able to install a virus on your device without your knowledge or consent. The virus may then be able to insert new, malicious code on your device that can monitor and manipulate your online activity.
What can viruses and other malware do to Android phones?
Malware is designed to generate revenue for cybercriminals.
Malware can steal your information, make your device send SMS messages to premium rate text services, or install adware that forces you to view web pages or download apps.
Info stealers can steal your contact list, your personal information, your location, your passwords, and more.
With the aid of malware, cybercriminals can access your devices and steal your information for their own use or to sell on the dark web.
Hackers also use ransomware to lock devices and encrypt personal data. Then they can demand a ransom payment from the victim in order to regain access to their files.Source: norton.com