Ransomware is a malware threat that can infect a device, blocking access to all or some of its contents (photos, videos, files, etc.) and then demanding a ransom to be paid to restore their availability.
how to prevent
Adopt Anti-Malware systems with dedicated ‘Anti-Ransomware’ modules
Using Firewalls with IPS ‘Intrusion Prevention System’ and Machine Learning systems against Ransomware
Structure backups that are not constantly online/on the same machine