When activated in the 'Advanced settings', the project field will be shown online and in the mobile application every time an expense is created.
With this field it is possible to make an overview of the costs per project. Both name and ID number will appear in your accounting report.
As an administrator you can create the projects for the users so that they can select the correct project out of a dropdown list.
In the details of a project, you have the possibility to limit it to groups and to make it a default value for groups.