An developer designs, codes, tests, debugs, and maintains software applications for IBM's platform, also known as IBM iSeries. They work with various programming languages like RPG, SQL, and CL to create and modify system functionalities. Their responsibilities include database management, system integration, and problem-solving to ensure optimal system performance. They also interact with clients or end-users to understand their needs and translate these into technical requirements. They often work closely with other IT professionals, such as system analysts and administrators, to ensure data security, system efficiency, and user satisfaction.