Avro is an open source row-based storage format. Avro has superior support for write operations when compared to the column-based storage supported by Apache Parquet. Avro allows columns to be added or modified (schema evolution). Avro is useful for ETL operations where there is a need to query all columns. 

When used as part of a data lakehouse, the combination of Avro and Parquet is useful in enabling the lakehouse to support incremental updates. Not all lakehouse projects use Avro. 

Related terms: Apache Parquet; data lakehouse; ETL

On the Onehouse website: