Dash is Plotly's open-source framework for building interactive analytical web applications in Python. It connects UI components such as dropdowns, sliders, tables, and controls directly to Python callbacks and Plotly visualizations, allowing data scientists to create web interfaces without building a separate JavaScript frontend.

Dash applications use a declarative, reactive programming model and can combine many inputs and outputs for cross-filtering, dashboards, reports, and custom data products. The framework is built on technologies including Plotly.js, React, and Flask while presenting developers with a primarily Python-facing API.

Dash is well suited to machine-learning, analytics, scientific, and internal-tool applications where teams want to turn Python analysis into an interactive web experience. The open-source framework covers application development, while Plotly also offers commercial deployment and enterprise tooling for organizations that need managed sharing and operational features.