What are the two fundamental sources for obtaining application software?

The two fundamental sources for obtaining application software are proprietary software and open-source software. Proprietary software is developed by companies and requires a purchase or license for use, often providing technical support and regular updates. Open-source software, on the other hand, is freely available for use, modification, and distribution, allowing users to customize it to their needs. Both sources offer unique advantages depending on the user's requirements and budget.