What is meant by adaptive maintenance?
Adapting the system to a clients needs that involves the operational system allowing businesses to continue; for example a change in VAT from 17.5% to 21%
What is corrective maintenance?
Correcting bugs and any problems that arise in the system not in the agreed specification; such as programming and coding errors.
What is perfective maintenance?
Perfects the system for the client as what they originally wanted the originalspecification may now require "cosmetic" changes to improve the appearance/usability of the system.