An ADO (ActiveX Data Objects) developer primarily designs, develops, and manages database solutions using Microsoft's ADO technology. They work with different data sources and services to create efficient, scalable data models. Their duties include writing queries, stored procedures, and functions, creating and maintaining databases, and ensuring data security and integrity. They also troubleshoot and optimize database systems for performance and reliability. Furthermore, they collaborate with other developers and team members to integrate databases with other applications, ensuring seamless data exchange and functionality. Their role is crucial in managing and manipulating data, which forms the backbone of any application.