The Change History Function is now preview — actually Google has released it a while ago, took it back and now released it again.
When loading data via ETL/ELT process into BigQuery it could make sense to realize a history of the data changes. It could help to detect problems with the data but also enables data analysis use cases like fraud detection or trends.
Before you have to implement such a data versioning logic by yourself:
But the new CHANGES change history function is a table-valued function that provides a history of table changes over a window of time and captures the following operations[1][2]: