A virus is a program or script written with an objective; collecting data, gaining control of a system, or opening a back door for future access to the system. A trojan is a program that caries a payload of a rootkit or a virus. A rootkit, much like a virus has an objective but functions at a lower level in the system. These are harder programs to identify and to remove. They function a the base layer of the operating system or can get into the boot sector of the operating system and infect the bios of the computer.

Malware stands for malicious software. it is any software designed with the intent of interrupting services. This includes trojans, viruses and rootkits.

A phishing attack is an attack attempting to gather sensitive information. A Spear Phishing attack is a targeted phishing attack.