1. Computer security
Computer security means protecting our computer system and the information they contain againts unwanted access, damage,destruction or modification.
E.g. hacker,crackers and script kiddie.

2. Type of security
Hardware security refers to security measure used to protect the hardware specifically the computer and its related documents. E.g: PC-locks, keyboard-locks, smart cards and biometric devices
Software/data security refers to the security measures used to protect the software and the loss of data files. E.g: activation code and serial number.
Network security refers to security measure used to protect the network system. E.g: firewall.

3. Types of security threats
Malicious code is known as a rogue program.
Virus is a program that can pass on the malicious code to other program by modifying them.
Trojan horse is a program which can perform useful and unexpected action.
Logic bomb is a malicious code that goes of when a specific condition occurs. E.g: time bomb.
Trapdoor or backdoor is a feature in a program that allows someone to access the program with special privileges.
Worm is a program that copies and spreads itself through a network.

4. Differences between worm and virus
Operates through the network.
Spreads copy of itself as a standalone program.
Spreads through any medium.
Spreads copies of itself as a program that attaches to other programs.

5. Hacker is a source of threat to security in computer
Hacker is a source of threat to security in computer. It is defined as unauthorised access to the computer system by a hacker.
Natural and environmental disaster are flood, fire, eartquakes, storms, tornados, excessive heat and inadequate power supply.
Theft consists of two types:
Computer is used to steal money, goods, information and resources.
Stealing of computer especially notebook and PDAs.

6. Security measures
Data backup is a program of file duplication. Backups of data application are necessary so that they can be recovered in case of an emergency.
Cryptography is a process of hiding information by altering the actual information into different representation, for example an APA can be written as I? X.

7. Antivirus is a program protects the computer againts viruses by identifying and removing any computer virus found in the computer memory, on storage media or incoming emeil files. Two thecnique are used to identify the virus are virus signature and inoculating a program files.
Anti-spyware is a program places on a computer without the users knowledge. It secretly collect information about the users.

8. Firewall is a piece of hardware or software which function in a network environment to prevent some communication forbidden by the security policy. Types of firewall are screening routers, proxy gateway and guard.
Human aspect of security measure refer to the user and also the intruder of a computer system. Human aspect are organisation self awareness. Organisational users self awareness an individual user self awareness,