A digital assault is an attack propelled by cybercriminals utilizing at least one PCs against a solitary or numerous PCs or systems. A digital assault can perniciously handicap PCs, take information, or utilize a ruptured PC as a dispatch point for different assaults. Cybercriminals utilize an assortment of strategies, including malware, phishing, ransomware, refusal of administration, among different techniques. Albeit most government offices and significant enterprises have completely sent individual devices as data safety efforts, focuses of assaults have extended to incorporate, other than government foundations, basic frameworks and explicit ventures and partnerships, calling for increasingly powerful counter measures. In this paper we have discussed about Cyber Attack and its types, its initiated and a major cyber-attacks in 21st century.