The core activity of Birrer Management GmbH encompasses four main areas: 1. **Furniture Business (Casa Gelsomina)**: Sales of furniture items under the brand 'Riviera Maison'. 2. **Photography (Birrer Photography)**: Creation of photographs on behalf of clients. 3. **Web Design and Software Development (Birrer Design and Development)**: Development of graphic designs, websites, and software solutions for clients. 4. **Business Management and Administration**: Overall management and administration of the various business areas by the owners and managing directors Angela and Stephan Birrer.