Your project will likely have deliveries or other dependencieswith other projects in MS Project. These dependencies can also be modeled with MS Project and will look exactly the same as links within projects: it is a black arrow going from one task to the other.
Big difference however, is that now the link starts from a task or milestone in one schedule and ends at a task or milestone in the other schedule.
For instance in Project ABC the task 'Assembly parts' has a dependency with task 'Delivery parts for assembly' in Project DEF. (the assembly can start after the delivery took place)
Project ABC
Project DEF
In the printscreen below the task 'Delivery parts for assembly' is a task from another project:
Link between projects
A 'link between projects' is a predecessor/successor relationship, just like a normal task relationship. The idea is that the link introduces a knock-on effect with regard to changes in timing; when the date of the predecessor in the first schedule shifts, the successor in the next schedule will shift accordingly.
By default, MS Project will show an acceptance window in the second schedule first, so that you are aware of how your schedule will change, before it is being changed. This window will be explained in a later topic.
Learn it the best way from the experts
You can create a 'link between projects' by having both schedules in one temporary file or master file and link them up in here. This concept we fully explain in our e-course Critical Path Management.
In the printscreen below the task 'Delivery parts for assembly' is a task from another project:
