Definition - What does RC4 mean?
RC4 is a symmetric key cipher and bite-oriented algorithm that encrypts PC and laptop files and disks as well as protects confidential data messages sent to and from secure websites. Output bytes require eight to 16 operations per byte. It is a stream cipher.
Techopedia explains RC4
RC4 can only be used one time to maintain its cryptographic security strength. Even so, it is considered very secure. RC4 was first designed by Rivest for RSA Security. A random number generator, also called a state machine, and each state transmission is outputted one bit of information at a time.