Program Maintenance Program maintenance refers to the modification of a program ,

after it has been completed. There are four kind of maintenance:

a. Corrective Maintenanceb. Adaptive Maintenancec. Preventive Maintenanced. Perfective Maintenance

Corrective Maintenance

Corrective maintenance refers to changes made to repair defects in the design, coding, or implementation of the system.  

Some errors might show up because of some unexpected situations, untested areas.

Most corrective maintenance problems rise soon after installation.

Corrective maintenance can be subdivided into "immediatecorrective maintenance" and "deferred corrective maintenance.

Modification of a software product performed after delivery to keep a software product sable in a changed or changing environment.

To accommodate changing needs, time to time, maintenance is done and is called adaptive maintenance.

This type of maintenance often occurs as a result of external influences or strategic changes within the company.

Modification of a software product performed after delivery to keep a software product sable in a changed or changing environment.

The way these are fixed is often in the form of a software patch that the user downloads or it is sent to their computer by the IT staff over the company network.

Preventive maintenance involves changes made to a system to reduce the chance of future system failure. 

The objective of perfective maintenance is to improve response time, system efficiency, reliability, or maintainability.

If possible errors could be anticipated, before they actually occur, the maintenance could be done to avoid them and the system down time can be saved.

Preventive maintenance is less likely to occur as compared to corrective maintenance.

PREVENTIVE MAINTENANCE

Perfective maintenance involves making enhancements to improve processing performance, interface usability, or to add desired, but not necessarily required, system features.

The objective of perfective maintenance is to improve response time, system efficiency, reliability, or maintainability.

During system operation, changes in user activity or data pattern can cause a decline in efficiency, and perfective maintenance might be needed to restore performance.

How to develop information that are easy to maintain?

1. The systems should be planned with an eye on the future.2. User specification should be correct.3. The system should be modular. 4. Documentation should be complete.5. Standards should be followed.6. Testing should be through.7. Adequate time should be allowed for development cycle.8. Attention should be paid to end-users , health and human factors should be

considered.9. The development team should be fully aware at the relationship of system design

and system maintenance.