In theory, project-based calculation may be used in nearly every area of activity, for example:
1. Construction – to distinguish between various sites
2. IT – to distinguish between various IT projects
3. Event organisation – to distinguish between various events
4. Also across areas of activity if one company is engaged in several businesses – to distinguish between construction and real estate, between marketing and training organisation, between several online shops, etc.

In the sales invoice view projects can only be used when a project has been added under settings. See more here:
Predefining project-based calculation.

To add different projects create a new invoice (in this example a sales invoice):
1. Open “Operations” and select “Invoices”.
2. In the invoice view click on the “Add project” icon at the end of the invoice line.
3. Select a project from the drop-down menu of the new pop-up window.

N.B. The same logic works for purchase invoices as well.

4. Receivables, payments and project-based salaries can be tied to a project.
For example:

5. You can see a report for every project under “Reports”.

The first part of a project shows (main project / subproject) a summary of sales and purchase invoices and a summary of employees and salaries.
The aggregate report considers all (also inactive) projects to which purchase invoices, sales invoices and salaries are bound.