.avro File — Apache Avro Data File

Apache Avro is a row-oriented data serialization system developed within the Apache Hadoop project. AVRO files contain data serialized with the Avro binary format along with the schema (defined in JSON) embedded in the file header, making files self-describing. This schema-with-data approach means consumers don't need a separate schema file to read Avro data. Avro supports rich data types including primitives, records, enums, arrays, maps, unions, and fixed-length byte arrays. The format features excellent schema evolution — readers can use a different (compatible) schema than the writer, enabling smooth data pipeline evolution. Avro is widely used in big data ecosystems for Hadoop data storage, Kafka message serialization (Confluent Schema Registry), data lake storage, and ETL pipelines. The binary encoding is compact and fast, while the JSON schema makes it accessible to developers. Avro supports code generation from schemas but also supports dynamic typing where data is accessed through a generic API without generated classes. The format supports compression within data blocks (deflate, snappy, zstd) and is splittable, allowing Hadoop MapReduce and Spark to process different parts of a file in parallel.