By default, all your tasks and projects are shown in Marvin. By using a Global Filter you can choose to hide all Tasks and Projects from one or more main Categories. This can be helpful, for example, when you're at Work and don't want to see any personal tasks, and vice-versa.
Creating a global filter
In the strategy settings choose whether you want your global filter to filter by your main categories or by using an advanced filter. By default, all your categories will be selected so if you choose to filter by categories, uncheck the ones you don't want to see. For example, if you want to see just the work-related stuff, leave only your work category checked.
Activating a global filter
Once you're done creating your global filters, you can activate one of them from the day/main view, by clicking on ☰ → Global Filters:
After you activate a global filter, the text in the menu dropdown will change so that you know which filter is active.