Bronze: the raw data
The Bronze layer contains data as it comes directly from the source. Think files, APIs or sensors. The data has not yet been cleaned or processed.
- Example: a CSV file containing sales orders, including typos, duplicate records or empty fields.
- Goal: keep everything as it is, so you can always go back to the original source.
Silver: the cleaned & properly modeled data
The Silver layer is cleaned up and standardized data. Here you remove errors, make sure all columns have the same meaning and establish relationships between tables. Also, these tables are well defined and reflect recognizable terms for the business and are therefore disconnected from source systems.
- Example: a table of sales orders with customer numbers validated, dates formatted correctly and duplicate records removed.
- Goal: reliable, consistent data ready for analysis.
Gold: the enriched data
The Gold layer is data set up specifically for reports or dashboards. Often this is already summarized or grouped together so that end users can start working with it immediately.
- Example: a table of monthly sales by region and product category.
- Goal: Instant insight for business users and managers.
Why is this important?
- Transparency: everyone knows where the data came from and how it was processed.
- Quality: errors are corrected in the appropriate step.
- Scalability: new resources can be easily added without having to redo everything.
Bronze, Silver and Gold in Power BI
In Power BI, you often see that the Gold layer is the source for dashboards and reports. Because the data has already been cleaned and summarized there, reports are faster, more reliable and easier to use. The Silver and Bronze layers are primarily used by data engineers to ensure that the data is properly prepared.
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