olemus
ISO/IEC/IEEE 24765
tarkvaratoote muutmine pärast kohaletoimetust,
varjatud defektide avastamiseks ja parandamiseks
enne nende ilmnemist tõrgetena
= modification of a software product after delivery to detect and correct latent faults in the software product before they are manifested as failures

ülevaateid
https://www.zibtek.com/blog/software-maintenance-understanding-the-4-main-types/

https://www.parkersoftware.com/blog/the-4-software-maintenance-categories-and-what-they-mean-for-your-users/

https://en.wikipedia.org/wiki/Software_maintenance

https://www.cram.com/essay/Advantages-And-Disadvantages-Of-Perfective-Maintenance/PCDBZTSHQG

vt ka
- adaptiivhooldus
- korrektiivhooldus
- preventiivhooldus