Hi,
today I will write about Milestones in MS PROJECT 2013! Before I started I would like to thank my MVP friend Oleksiy Prosnitskyy from Ukraine (http://msprojectmvp.blogspot.com/), who ALWAYS read my Blog, and he is the first who notice me about any error in it. Thank you my friend, I appreciate it so much!
What is Milestone? According to Wikipedia: “Milestones are tools used in project management to mark specific points along a project timeline. These points may signal anchors such as a project start and end date, a need for external review or input and budget checks, among others. In many instances, milestones do not impact project duration. Instead, they focus on major progress points that must be reached to achieve success”
So it can be a end of Project phase, end of whole Project, Contract signed, etc.! According to that Milestone has 0 days duration! Milestone is achieved or not! Let me give you an example in MS PROJECT 2013. Here is the Project:
As you can see, I have activities, and Milestone, when Contract is signed, so after that we can continue with Executing phase of the Project (not shown here). When I put zero days duration, Task is automatically marked as a Milestone. To see that Double Click on this Task, and you can see it here:
When Task has Duration greater than Zero days, I can Mark that Task as a Milestone as well. Just follow the step above.
Now let me assign some Resources to Tasks:
As you can see I put to Task 5 – Contract Signed 2 days duration. When I Mark it as a Milestone, and I will get:
You can see that Contract Signed has Mark as a Milestone, and it Predecessor looks like it has LAG 2 days. Now I will look at Task Usage View:
As you can see, this “Milestone” is in fact, Activity, like any other. It behaves like Activity, but it is only Mark as Milestone!
If you ask me a question: “Why should I Mark Task with Duration greater than zero, as a Milestone?”, My answer will be: “DO NOT! Be consistent and always, ALWAYS put zero days for Milestone.” But that is my opinion, of course. According to Wikipedia, PMI, and other Project Management organization, Milestone is a check point, and it should have 0 days Duration.
Of, course you can disagree with that.
Regards!
Nenad Trajkovski 
I always like to appreciate you for your contribution to the growth of the Project Management profession. I read in a book that milestones, in addition to the fact that they have zero duration, don’t have any resource attached to them since it is a “state” in the life of a project. Please how do you respond to this?
Well,
if someone has to check this state, I always prefer to put Resource(s) on it