What is the Medallion Architecture? Can you explain?

The Medallion Architecture is a layered approach to building data lakes that emphasizes data quality, governance, and reusability. It consists of three primary layers:

1. Bronze (Raw) – Ingested data in its native format (JSON, Parquet, CSV, etc.) with minimal transformation. This layer preserves the original source for auditability and debugging.
2. Silver (Cleansed) – Data is cleaned, deduplicated, and enriched. Business rules are applied, missing values handled, and schema is enforced. The goal is to produce a reliable, query‑ready dataset.
3. Gold (Business‑Ready) – Aggregated, curated, and optimized for specific analytics or reporting use cases. This layer often contains materialized views, dashboards, or machine‑learning training data.

Key benefits include:

• Incremental Processing – Each layer can be refreshed independently, reducing compute costs.
• Data Lineage – Clear traceability from raw to business‑ready data.
• Governance – Policies can be applied at each stage (e.g., masking sensitive data in Bronze, enforcing quality in Silver).
• Reusability – Multiple downstream consumers can share the same Silver or Gold datasets.

Implementations typically use Spark, Delta Lake, or similar technologies to support ACID transactions, schema evolution, and time‑travel across layers.