Software activation usually relies on asymmetric cryptography. The software developer holds a private key to sign activation codes, while the software contains a public key to verify them.
The term in the search query refers to the modified, cracked version of the software's binary files that allows the keygen to work. Why Using "Digital Insanity" Patches is Extremely Risky
Here is an article discussing the technical and security implications of software licensing and the risks associated with unauthorized patches.
Here you'll find all collections you've created before.