[SOLVED] Date of Project and Activities

I have a question about the start and end of the project.
For example, I have a project ABCD with a start is 04/15/2016 and the project's end date is 04/30/2016.
The reason is that the activity of the project must be included in that period. But I can make the activity has a start date and an end date of 25/05/2016 and 05/30/2016. Thanks admin help explain?
Thank you very much.

I have a project ABCD with a start is 04/15/2016 and the project's end date is 04/30/2016.

But I can make the activity has a start date and an end date of 25/05/2016 and 05/30/2016.

These dates are validated or planned dates?

Yes, projects have validated. But I do not know how to planned, because it is not for the manually enter

As Ad said, the day of activity used to determine the start and end of the project.On my project, I set the start date and end date is 04/01/2016 04/20/2016. So my activities can make out the end of the project, ie I can create activities with a start and end date is 05/05/2016 05/20/2016. Meanwhile, my project end date will depend on the closing date of the last activity? Is it right?
There's something I do not understand much.
I think the day of the activities will be in the start date and end date of the project rather.
Thanks for the help