Until a ransom is paid, ransomware, a crypto virology virus, tries to disclose or constantly restrict access to the accused's confidential information. While simple ransomware may merely lock the computer without deleting any files, more sophisticated viruses employ a strategy called crypto viral blackmail. Files belonging to the victim are encrypted, rendering them unavailable, and a ransom demand is made to unlock them. Data belonging to the user is encrypted, making it illegible, and a ransom is demanded to open them. The characteristics of ransomware, its functionality, and its variations are addressed in this study. A thorough literature study is conducted to identify the research areas, defence mechanisms against ransomware assaults, and potential future applications of the prior studies in this field.