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.