What is cyber security? What are the various common security threats?

Cyber security is the practice of protecting computers, servers, networks, programs and data from theft, damage, unauthorized access or disruption. Its goal is the CIA triad: Confidentiality (only allowed persons see data), Integrity (data is not altered wrongly), Availability (systems work when needed). In Nepal, the Electronic Transaction Act 2063 and ICT Policy 2072 legally support it.

Common security threats:

1. Malware: Malicious software — Virus (attaches to files), Worm (spreads itself), Trojan (hides in useful software), Ransomware (locks files for money), Spyware (secretly records). Prevention: updated antivirus.

2. Phishing: Fake email/SMS/website that looks like bank or office to steal passwords. Example: “Your Khalti blocked, click link”. Prevention: check sender, never share OTP.

3. Hacking / Unauthorized access: Breaking passwords or exploiting weak software to enter systems. Prevention: strong passwords + MFA.

4. DoS/DDoS: Flooding server with fake traffic so real users cannot open site. Example: government result site down on result day due to overload/attack. Prevention: firewall, load balancer.

5. Social engineering: Tricking people, not computers — fake phone call as “IT staff” asking password. Prevention: awareness training.

6. Data theft / Insider misuse: Pen-drive copy of office data by staff. Prevention: access control, USB policy.

For exam, write definition + any 5 threats with one-line example and one-line prevention to show complete understanding.