Why does it change?
Software changes does not change primarily because it
doesn’t work right
Maintenance in software is different than maintenance for
automobiles
But rather because the technological, economic, and
societal environment in which it is embedded changes
This provides a feedback loop to the software
The software is usually the most malleable link in the chain, hence
it tends to change
Counterexample: Space shuttle astronauts have thousands of extra
responsibilities because it’s safer than changing code