If you want to be security professional even hacker you should know these terms , u may know or not i just share with you 

1.Adware - Adware is software designed to force pre-chosen ads to display on your system. Some adware is designed to be malicious and will pop up ads with such speed and frequency that they seem to be taking over everything, slowing down your system and tying up all of your system resources. When adware is coupled with spyware, it can be a frustrating ride, to say the beast. 

2.Back Door - A back door is a point of entry that circumvents normal security and can be used by a cracker to access a network or computer system. Usually back doors are created by system developers as shortcuts to speed access through security during the development stage and then are overlooked and never properly removed during final implementation. Sometimes crackers will create their own back door to a system by using a virus or a Trojan to set it up, thereby allowing them future access at their leisure. 

3.Black Hat - Just like in the old westerns, these are the bad guys. A black hat is a cracker. To add insult to injury, black hats may also share information about the “break in” with other black hat crackers so they can exploit the same vulnerabilities before the victim becomes aware and takes appropriate measures… like calling Global Digital Forensics! 

4. Bot - A bot is a software “robot” that performs an extensive set of automated tasks on its own. Search engines like Google use bots, also known as spiders, to crawl through websites in order to scan through all of your pages. In these cases bots are not meant to interfere with a user, but are employed in an effort to index sites for the purpose of ranking them accordingly for appropriate returns on search queries. But when black hats use a bot, they can perform an extensive set of destructive tasks, as well as introduce many forms of malware to your system or network. They can also be used by black hats to coordinate attacks by controlling botnets. 

5. Botnet – A botnet is a network of zombie drones under the control of a black hat. When black hats are launching a Distributed Denial of Service attack for instance, they will use a botnet under their control to accomplish it. Most often, the users of the systems will not even know they are involved or that their system resources are being used to carry out DDOS attacks or for spamming. It not only helps cover the black hat’s tracks, but increases the ferocity of the attack by using the resources of many computer systems in a coordinated effort. 

6. Cookies – A cookie is a small packet of information from a visited webserver stored on your system by your computer’s browser. It is designed to store personalized information in order to customize your next visit. For instance, if you visit a site with forms to fill out on each visit, that information can be stored on your system as a cookie so you don’t have to go through the process of filling out the forms each time you visit. 

7. Cracker - When you hear the word hacker today, in reality it is normally referring to a cracker, but the two have become synonymous. With its origin derived from “safe-cracker” as a way to differentiate from the various uses of “hacker” in the cyber world, a cracker is someone who breaks into a computer system or network without authorization and with the intention of doing damage. A cracker may destroy files, steal personal information like credit card numbers or client data, infect the system with a virus, or undertake many others things that cause harm. This glossary will give you an idea of what they can do and some of the means they use to achieve their malicious objectives. These are the black hats. 

8. Denial of Service Attack (DOS) – A Denial of Service attack is an attack designed to overwhelm atargeted website to the point of crashing it or making it inaccessible. Along with sheer numbers and frequency, sometimes the data packets that aresent are malformed to further stress the system trying to process the server requests. A successful Denial of Service attack can cripple any entity that relies on its online presence by rendering their website virtually useless. 

9. Distributed Denial of Service Attack (DDOS) - A Distributed Denial of Service attack is done with thehelp of zombie drones (also known as a botnet) under the control of black hats using a master program to command them to send information anddata packets to the targeted webserver from the multiple systems under their control. This obviously makes the Distributed Denial of Service attack even more devastating than a Denial of Service attack launched from a single system, flooding the target server with a speed and volume that is exponentially magnified. As is normally the case with zombie drones and botnets, this is often done without the user of the controlled system even knowing they were involved. 

10. Dumpster Diving - The act of rummaging through the trash of an individual or business to gather information that could be useful for a cyber criminal to gain access to a system or attain personal information to aid them in identity theft or system intrusion. One person’s garbage can indeed be a cyber criminal’s treasure. 

11.Easter Egg - A non-malicious surprise contained in a program or on a circuit board installed by the developer. It could be as simple as a text greeting, a signature, or an image embedded on a circuit board,or comprise a more complex routine, like a video or a small program. The criteria that must be met to be considered an Easter Egg are that it be undocumented, non-malicious, reproducible to anyone with the same device or software, not be obvious, and above all – it should be entertaining! 

12.Firewall - A firewall is a security barrier designed to keep unwanted intruders “outside” a computer system or network while allowing safe communication between systems and users on the “inside” of the firewall. Firewalls can be physical devices or software-based,or a combination of the two. A well designed and implemented firewall is a must to ensure safe communications and network access and should be regularly checked and updated to ensure continued function. Black hats learn new tricks and exploit new techniques all the time, and what worked to keep them out yesterday may need to be adjusted or replaced over time. 

13.Gray Hat – A gray hat, as you would imagine, is a bit of a white hat/black hat hybrid. Thankfully, like white hats, their mission is not to do damage to a system or network, but to expose flaws in system security. The black hat part of the mix is that they may very well use illegal means to gain access to the targeted system or network, but not for the purpose of damaging or destroying data: they want to expose the security weaknesses of a particular system and then notify the “victim” of their success. Often this is done with the intent of then selling their services to help correct the security failure so black hats can not gain entry and/or access for more devious and harmful purposes.