A developer is primarily responsible for programming, developing, and maintaining the MAS ERP system, a comprehensive enterprise management solution. Their tasks involve customizing the system according to clients' needs, troubleshooting any issues, integrating it with other software, and ensuring its optimal performance. They also conduct system tests, provide user support, and may be involved in training users. They must understand SQL Server databases, as they often work with T-SQL, and usually need knowledge of VB.NET or C#. Their work helps companies streamline their processes, making them more efficient and effective.