A software release life cycle is the sum of the stages of development and maturity for a piece of computer software: ranging from its initial development to its eventual release, and including updated versions of the released version to help improve software or fix software bugs still present in the software. 

Usage of the "alpha/beta" test terminology originated at IBM. As long ago as the 1950s (and probably earlier), IBM used similar terminology for their hardware development. "A" test was the verification of a new product before public announcement. "B" test was the verification before releasing the product to be manufactured. "C" test was the final test before general availability of the product. As software became a significant part of IBM's offerings, the alpha test terminology was used to denote the pre-announcement test and beta test was used to show product readiness for general availability. Martin Belsky, a manager on some of IBM's earlier software projects claimed to have invented the terminology. IBM dropped the alpha/beta terminology during the 1960s, but by then it had received fairly wide notice. The usage of "beta test" to refer to testing done by customers was not done in IBM. Rather, IBM used the term "field test".
What term describes differen parts of program development?
A software release life cycle is the sum of the stages of development and maturity for a piece of computer software: