1. Crimes that aim at computer networks or devices. These types of crimes involve different threats (like virus, bugs etc.) and denial-of-service (DoS) attacks. 
2. Crimes that use computer networks to commit other criminal activities. These types of crimes include cyber stalking, financial fraud or identity theft.

Classification of Cyber Crime: 

1. Cyber Terrorism – 
   Cyber terrorism is the use of the computer and internet to perform violent acts that result in loss of life. This may include different type of activities either by software or hardware for threatening life of citizens. 
   In general, Cyber terrorism can be defined as an act of terrorism committed through the use of cyberspace or computer resources. 
    
2. Cyber Extortion – 
   Cyber extortion occurs when a website, e-mail server or computer system is subjected to or threatened with repeated denial of service or other attacks by malicious hackers. These hackers demand huge money in return for assurance to stop the attacks and to offer protection. 
    
3. Cyber Warfare – 
   Cyber warfare is the use or targeting in a battle space or warfare context of computers, online control systems and networks. It involves both offensive and defensive operations concerning to the threat of cyber attacks, espionage and sabotage. 
    
4. Internet Fraud –
   Internet fraud is a type of fraud or deceit which makes use of the Internet and could include hiding of information or providing incorrect information for the purpose of deceiving victims for money or property. Internet fraud is not considered a single, distinctive crime but covers a range of illegal and illicit actions that are committed in cyberspace. 
    
5. Cyber Stalking – 
   This is a kind of online harassment wherein the victim is subjected to a barrage of online messages and emails. In this case, these stalkers know their victims and instead of offline stalking, they use the Internet to stalk. However, if they notice that cyber stalking is not having the desired effect, they begin offline stalking along with cyber stalking to make the victims’ lives more miserable.

Challenges of Cyber Crime:

1. People are unaware of their cyber rights-
   The Cybercrime usually happen with illiterate people around the world who are unaware about their cyber rights implemented by the government of that particular country.
    
2. Anonymity-
   Those who Commit cyber crime are anonymous for us so we cannot do anything to that person.
    
3. Less numbers of case registered-
   Every country in the world faces the challenge of cyber crime and the rate of cyber crime is increasing day by day because the people who even don’t register a case of cyber crime and this is major challenge for us as well as for authorities as well.
    
4.  Mostly committed by well educated people-
   Committing a cyber crime is not a cup of tea for every individual. The person who commits cyber crime is a very technical person so he knows how to commit the crime and not get caught by the authorities. 
    
5. No harsh punishment-
   In Cyber crime there is no harsh punishment in every cases. But there is harsh punishment in some cases like when somebody commits cyber terrorism in that case there is harsh punishment for that individual. But in other cases there is no harsh punishment so this factor also gives encouragement to that person who commits cyber crime.

Prevention of Cyber Crime: 

Below are some points by means of which we can prevent cyber crime: 

1. Use strong password – 
   Maintain different password and username combinations for each account and resist the temptation to write them down. Weak passwords can be easily cracked using certain attacking methods like Brute force attack, Rainbow table attack etc, So make them complex. That means combination of letters, numbers and special characters.
    
2. Use trusted antivirus in devices –
   Always use trustworthy and highly advanced antivirus software in mobile and personal computers. This leads to the prevention of different virus attack on devices. 
    
3. Keep social media private –
   Always keep your social media accounts data privacy only to your friends. Also make sure only to make friends who are known to you. 
    
4. Keep your device software updated –
   Whenever you get the updates of the system software update it at the same time because sometimes the previous version can be easily attacked. 
    
5. Use secure network –
   Public Wi-Fi are vulnerable. Avoid conducting financial or corporate transactions on these networks.
    
6. Never open attachments in spam emails –
   A computer get infected by malware attacks and other forms of cybercrime is via email attachments in spam emails. Never open an attachment from a sender you do not know.
7. Software should be updated – Operating system should be updated regularly when it comes to internet security. This can become a potential threat when cybercriminals exploit flaws in the system.