The term vulnerability is used to describe weaknesses in software or hardware arising out of a programming flaw which gives way to the access of computers by people with malicious intent. Vulnerabilities are used by people with malicious intent to wipe, steal, and change the data oninformation systems or to attack other systems.

The word ‘bot’ is generated from ‘Robot’. A bot program can independently work out automatic processes. Bots can be as innocent as those used in search engines and in getting information about websites. But bots can be used for the performance of other more different and malicious acts too. Bots for instance, can be used in accessing all the data on your computer and in fraudulent acts against other individuals or organizations.

If your computer is infected by bot, this frequently means that you are a part of a big scale worldwide bot network. Such bot networks are called botnet. A botnet can be centrally controlled by a single person. Botnets could be used or rented out by their owners for purposes of fraud.
Distributed Denial of Service (DDoS) Attacks
DDoS attacks hamper the service of information systems. DDoS attacks are realized by sending e-mails to a system from various computers, and by routing certain network traffic. Under the circumstances, your internet connection or server cannot cope with such heavy traffic and comes to a standstill. Sometimes, hundreds of thousands computers can be attackers.
Unsolicited bulk e-mail is called SPAM. Unsolicited e-mails are generally sent for advertisementpurposes. Content of these messages is not important but their being sent in very large numbers is.
Keyboard Recorder
The keyboard recorder is a program recording keystrokes. Advanced keyboard recorders can record mouse actions and screen images as an image file. The keyboard recorder later sends the records it keeps to people of malicious intent by e-mail or through other channels. Keyboard recorders are a type of spy software.
These are acts to gather personal information. Personal information gathered in this way is used in fraudulent acts in banking transactions and doing bulk shopping by using credit cards.

Man-in-the-Middle Attack 
This is an attack type where the attacker is positioned between the client and server. In such attacks the attacker is identified by the client as the serves; and by the server as the client. By positioning in the middle, the attacker is able to spy on or change the data flow between client and server.

Port Scanning
A port scan is a check made on each computer port to quickly learn which computer network services the computer provides. This can be accomplished in a short time through automatic software. At the end of the scanning process, the attacker gets information about which vulnerabilities can be used on the computer.
Adware is a small programs installed in your computer without your knowledge. It can be contained infree software. Adware allows pop-up advertisement to appear on your screen and tracks your internet activity. Adware records all the pages you surf on the internet. This information is regularly sent to the adware program vendor and used in sending you advertisements which might be of particular interest to you.
Zero Day Vulnerability
These are vulnerabilities contained in any product without the knowledge of the product vendor or other individuals and organizations involved in computer security; but known and used by attackers.
A worm is a self-replicating program designed to send copies of itself to as many computers as possible. A worm is different from a virus in that it does not need to attach itself to an existing program in order to spread.
The term scam is used to describe computer fraud to steal money from people.
Trojan horse
A Trojan horse is a seemingly innocent and legal program but includes malicious functions. For instance, when you run a seemingly innocent game program or image file, you can play the game or watch the image to your expectations. But the vendor or distributor of the game program or image file can take over or give harm to your computer.
A virus is software acting secretly without the knowledge of the computer owner. Viruses are sometimes innocent but generally they act maliciously like spreading your confidential files. The difference between a virus and other malicious software is that a virus infects files and copies itself as soon as the attacker releases it.
This is a common term used for all malicious software. Viruses, worms, keyboard recorders, spy software and adware are all malicious software.
Zombie Computer
Computers infected by bot are called zombie computers. These computers are a part of botnet and used in internet offences.