Salesforce trigger list/map values on insert/update/delete/undelete

This table shows us when Id exists in trigger:

	insert	update	delete	undelete
before	null	Id	Id	-
after	Id	Id	Id	Id

And this one shows what values of Map/List we have on different stages of trigger work:

Execution	Method	insert	update	delete	undelete
before	trigger.new()	List	List	null	-
before	trigger.newMap()	null	Map	null	-
before	trigger.old()	null	List	List	-
before	trigger.oldMap()	null	Map	Map	-
after	trigger.new()	List	List	null	List
after	trigger.newMap()	Map	Map	null	Map
after	trigger.old()	null	List	List	null
after	trigger.oldMap()	null	Map	Map	null

UTD: Code.

Trigger on Contact:

trigger ContactTrigger on Contact ( before insert, after insert,
                                    before update, after update,
                                    before delete, after delete,
                                    after undelete ) {
    if( Trigger.isBefore ){
        if( Trigger.isInsert ){
            System.debug( LoggingLevel.INFO,'@@@before insert new: ' + Trigger.new );
            System.debug( LoggingLevel.INFO,'@@@before insert newMap: ' + Trigger.newMap );
            System.debug( LoggingLevel.INFO,'@@@before insert old: ' + Trigger.old );
            System.debug( LoggingLevel.INFO,'@@@before insert oldMap: ' + Trigger.oldMap );
        }
        if( Trigger.isUpdate ){
            System.debug( LoggingLevel.INFO,'@@@before update new: ' + Trigger.new );
            System.debug( LoggingLevel.INFO,'@@@before update newMap: ' + Trigger.newMap );
            System.debug( LoggingLevel.INFO,'@@@before update old: ' + Trigger.old );
            System.debug( LoggingLevel.INFO,'@@@before update oldMap: ' + Trigger.oldMap );
        }
        if( Trigger.isDelete ){
            System.debug( LoggingLevel.INFO,'@@@before delete new: ' + Trigger.new );
            System.debug( LoggingLevel.INFO,'@@@before delete newMap: ' + Trigger.newMap );
            System.debug( LoggingLevel.INFO,'@@@before delete old: ' + Trigger.old );
            System.debug( LoggingLevel.INFO,'@@@before delete oldMap: ' + Trigger.oldMap );
        }
    }
    if( Trigger.isAfter ){
        if( Trigger.isInsert ){
            System.debug( LoggingLevel.INFO,'@@@after insert new: ' + Trigger.new );
            System.debug( LoggingLevel.INFO,'@@@after insert newMap: ' + Trigger.newMap );
            System.debug( LoggingLevel.INFO,'@@@after insert old: ' + Trigger.old );
            System.debug( LoggingLevel.INFO,'@@@after insert oldMap: ' + Trigger.oldMap );
        }
        if( Trigger.isUpdate ){
            System.debug( LoggingLevel.INFO,'@@@after update new: ' + Trigger.new );
            System.debug( LoggingLevel.INFO,'@@@after update newMap: ' + Trigger.newMap );
            System.debug( LoggingLevel.INFO,'@@@after update old: ' + Trigger.old );
            System.debug( LoggingLevel.INFO,'@@@after update oldMap: ' + Trigger.oldMap );
        }
        if( Trigger.isDelete ){
            System.debug( LoggingLevel.INFO,'@@@after delete new: ' + Trigger.new );
            System.debug( LoggingLevel.INFO,'@@@after delete newMap: ' + Trigger.newMap );
            System.debug( LoggingLevel.INFO,'@@@after delete old: ' + Trigger.old );
            System.debug( LoggingLevel.INFO,'@@@after delete oldMap: ' + Trigger.oldMap );
        }
        if( Trigger.isUnDelete ){
            System.debug( LoggingLevel.INFO,'@@@after undelete new: ' + Trigger.new );
            System.debug( LoggingLevel.INFO,'@@@after undelete newMap: ' + Trigger.newMap );
            System.debug( LoggingLevel.INFO,'@@@after undelete old: ' + Trigger.old );
            System.debug( LoggingLevel.INFO,'@@@after undelete oldMap: ' + Trigger.oldMap );
        }
    }
}

Code for console run:

Contact contactItem = new Contact( LastName = 'Test' );
insert contactItem;

contactItem.LastName = 'Testing';
update contactItem;

delete contactItem;

//contactItem = new Contact( Id=contactItem.Id );
undelete contactItem;

Enjoy.