What is a medallion architecture in data engineering?
A medallion architecture is a data engineering concept.  The idea is that system source data or system of record data is landed in a bronze layer.  In the bronze layer data is not changed, and it should match the source system exactly even if there are data quality issues.  Next in the silver layer the raw daw from bronze is transformed and joined together with data quality applied and landed in silver.  Next in the gold layer are produced datasets which are silver datasets joined together and enriched with other data like machine learning model output.  These gold datasets are then what are used and served up by the business in dashboards and reporting.