The main challenge of software scalability involves ensuring that applications can handle increasing loads without performance degradation. As user demand grows, systems must manage larger volumes of data and more concurrent users efficiently. Poor scalability can lead to slow response times or outages, affecting the overall user experience. Developers face the challenge of designing architectures that are both robust and adaptable, requiring thorough testing and optimization. Strategies such as load balancing, horizontal scaling, and using microservices are often employed to address these challenges.