You can create custom fields and add codes/tags to any activity on the table

Doing so will help you create powerful filters allowing you to view the project in useful ways. Read about it here.

To add a code to any activity: select the cell corresponding to that activity and field.

You can start typing, and a list of options will appear here. Or you can click on the arrow on the right of the cell and select a tag.

You can also create a new code/tag right here by typing it and pressing enter or clicking on create new option at the bottom of the dropdown