“Malware” is short for “malicious software” - computer programs designed to infiltrate and damage computers without the users consent. “Malware” is the general term covering all the different types of threats to your computer safety such as viruses, spyware, worms, trojans, rootkits and so on.

Definition: A computer virus is a malicious software program loaded onto a user’s computer without the user’s knowledge and performs malicious actions.

Definition: Spyware is the term given to a category of software which aims to steal personal or organisational information. It is done by performing a set of operations without appropriate user permissions, sometimes even covertly. General actions a spyware performs include advertising, collection of personal information and changing user configuration settings of the computer.

Description: A Spyware is generally classified into adware, tracking cookies, system monitors and Trojans. The most common way for a spyware to get into the computer is through freeware and shareware as a bundled hidden component. Once a spyware gets successfully installed, it starts sending the data from that computer in the background to some other place.

 These days spywares are usually used to give popup advertisements based on user habits and search history. But when a spyware is used maliciously, it is hidden in the system files of the computer and difficult to differentiate.

 One of the simplest and most popular, yet dangerous are Keyloggers. It is used to record the keystrokes which could be fatal as it can record passwords, credit card information etc. In some shared networks and corporate computers, it is also intentionally installed to track user activities.

 Presence of spyware in a computer can create a lot of other troubles as spyware intended to monitor the computer can change user preferences, permissions and also administrative rights, resulting in users being locked out of their own computer and in some cases, can also result in full data losses. Spyware running in the background can also amount to increased number of processes and result in frequent crashes. It also often slows down a computer.

 Best way to remain protected is to use good Antivirus/Antispyware software. More importantly, be careful while installing freeware applications by properly removing the unnecessarily checked options by default. 

 Definition - What does Spam mean? 

Spam refers to the use of electronic messaging systems to send out unrequested or unwanted messages in bulk. 

The difficulty with stopping spam is that the economics of it are so compelling. While most would agree that spamming is unethical, the cost of delivering a message via spam is next to nothing. If even a tiny percentage of targets respond, a spam campaign can be successful economically. 

 A cracker is an individual who performs cracking, or the process of breaking into a computer or a network system. A cracker might be performing cracking for malicious activities, profit, for certain nonprofit intentions or causes, or just for a challenge. Some crackers break into a network system deliberately to point out the flaws involved in that network's security system. In most cases, crackers aim to gain access to confidential data, get hold of free software applications, or carry out malicious damage to files.