what are the main types of System Maintenance? (with brief explanation)

good answer Anas and Whaeeb

There are two main type of system maintenance :
1- annual maintenance that take action every period of time like every year or more depinding on manufacturer instructions and the environment of operation 
2- argent maintenance that take action when the system fail or except to fail and it will be fast and reliable to insure that the system remainns healthy.

There are many types of maintenance as follow:
1- Preventive / Periodical  maintenance which take action in fixed period weekly, monthly, quarterly, semi annualy and annualy.

2- Corrective maintenance which take action when there is troubleshooting happend in the machine.

3- Total Productive manintenace which take action in different wise  such as      * expectation of parts failuer.
 to ensure  

1.Preventive Maintenance : Sceduled maintenance with frequency according manuals or according your expeience.

2.Corrective Maintenance : According urgent faiulers of machine.

3.Predective Maintenance : Collection of data and analyze it according saved data base or qualification by specialized person and the a corrective or preventive maintenance should be issued.

The Reliability Centred Maintenance (RCM)technique will be adopted to focus the results oriented cost effective maintenance plan.

There are three things to be considered on maintenance system as follows:

- PPM ( Preventive and Predictive Maintenance)= Planned Maintenance activities that have been set up based on maintenance strategies and tactics.

- PM (Preventive Maintenance)= Generally calendar-based maintenance activity.

- PdM (Predictive Mantenance) = Generally condition-based maintenance activity.

Hope this beneficial to use for maintenance planning.