The term "crack" means the action of removing the copy protection from retail software.
A crack is a program, set of instructions or patch used to remove copy protection from a piece of software or to unlock
features from a demo or time-limited trial. Sometimes a person will write a crack to show that they are smarter than the copy protection scheme.
There are also crack groups who work together in order to crack the software.
What is a Keygen?
The term "keygen" means a small program that will generate a cd key, serial number, activation number, license code or registration number for a piece of software. Keygen is short for Key Generator.
A keygen is made available through crack groups for free download.
What is a Serial?
The term "serial" in warez context means a unique number or code which identifies the license of the software as being valid.
All retail software uses a serial number of some type, and the installation requires the user to enter a valid serial number to continue.