Dagster is a data orchestrator that helps build data pipelines, similar to how Django is used for building web applications. It enables users to produce data assets and then re-run these processes incrementally when the asset becomes outdated. Dagster has three key differentiators: local development and testing, software-defined assets (SDAs), and decoupling pipelines from the environment. These features make it easier for data engineers and machine learning engineers to build complex data applications. The tool provides a framework for building data pipelines, including tools for ingesting data, combining and transforming it, storing it in a place where it can be used, and re-running these processes when necessary. Dagster is designed for users who need to bridge the engineering and data worlds, providing a platform for managing complex data applications.