A backdoor is a means often employed by hackers, governments, IT people to get remote access to your device without your knowledge or consent. Backdoors can be installed on your system through malware that exploits your security vulnerabilities. It can also be directly installed in your system’s hardware/firmware. Using backdoors, hackers and cybercriminals can use your device for surveillance, theft, cryptojacking, sabotage, malware attack, and more. 

A backdoor can be installed by software and hardware developers for remote tech support purposes. Nevertheless, in most cases, backdoors are installed by cybercriminals or governments to gain access to your device, network, or software. Any malware that provides hackers with access to your system can be categorized as a backdoor. This includes rootkits, trojans, spyware, cryptojackers, keyloggers, worms, and ransomware.
To Read the full article click the link below-
What is Backdoor and How Can We Protect Ourselves from Backdoor Virus Attacks?