How can I duplicate / copy projects, tasks,...

To duplicate / copy a project and it's tasks click on the Info icon next to the project title either on the dashboard or on your project board.

Now click on … at the top right of the project dialog and click on Duplicate...

 

You are then able to set a title and description for your duplicated project and to select what you want to duplicate:

Duplicate Options

Click on Continue to duplicate the project.

That's it, you are now able to duplicate projects and can even use them as templates.