AWS developers work on a wide variety of applications, reflecting the versatility of the AWS platform. They can build web applications, mobile backends, microservices, serverless applications, and more. They might work on developing data pipelines, setting up data lakes, creating AI/ML models, or deploying IoT applications. They could be building enterprise-level applications that need to scale to serve millions of users, or they could be developing more niche applications for specific business needs. The type of application will depend heavily on the business requirements and could utilize any combination of the 200+ services provided by AWS.