Dagster is a modern data orchestration platform designed around software-defined assets—a declarative approach where data pipelines are modeled as first-class objects rather than task-based workflows. Originally developed to address limitations in traditional orchestrators like Airflow, it provides data-aware orchestration with built-in observability, type-checking, and testing capabilities. Core to Dagster's philosophy is treating data assets (tables, files, models) as the primary abstraction rather than tasks, enabling automatic lineage tracking, easier debugging, and a more intuitive mental model for data engineers. The framework supports both asset-based and op-based (task-based) workflows, though assets are recommended for most use cases as they provide superior observability and composability out of the box.