W. H. Inmon's 'Building the Data Warehouse' published

This seminal book formally introduced and defined the concept of the data warehouse, a structured repository for business intelligence. It laid out the architectural principles and the necessity of data integration.

Significance

By defining the data warehouse, Inmon implicitly created the blueprint for ETL, making it a recognized and essential component of any enterprise-level analytics strategy. It provided the 'why' for ETL.