Starting or rescheduling a task X days earlier / later than planned will move all successor tasks for the same nr of days
Start at planned start date
When a task is planned to start at 10 November and it actually starts at 10 November, the planning for all successor tasks will remain the same.
Start later
When a task is planned to start at 10 November and it actually starts later or it's rescheduled to a later date, for example on 22 November, all successor tasks and the successor tasks of these tasks (continue until the end of the stage) will be moved later in time for the same number of days as the task is started later than planned.
In case there is a 'gap' in between tasks, this gap remains in the planning. So the tasks are moved in the exact same relative position to each other, later in time.
Start earlier / reschedule to earlier date
When a task is planned to start at 10 November and it actually starts earlier or it's rescheduled to an earlier date, for example on 5 November, all successor tasks and the successor tasks of these tasks (continue until the end of the stage) will be moved earlier in time for the same number of days as the task is started earlier than planned. However, if a task which is supposed to be moved earlier in time has a 'blocking' predecessor (because this predecessor is not moved), the task is only moved up to this predecessor task. So the predecessor task end date + 1 will then become the new start date of the task.
NOTE
Tasks will only be rescheduled if the project is in Task planning mode and they have the status Planned.