Avro is a data serialization system developed within the Apache Hadoop project. It provides a rich data structure, a compact, fast, binary data format, a container file to store persistent data, remote procedure call (RPC) and simple dynamic language integration. Avro uses JSON for defining data types and protocols, and serializes data in a compact binary format. Its primary use is in Hadoop, where it is used for data serialization and data exchange services. Avro is particularly well-suited for applications that require schema evolution, as it stores the schema along with the data. This allows readers to process data even if the schema has changed since the data was written. Avro's schema evolution capabilities, combined with its efficient binary format, make it a popular choice for data storage and exchange in big data environments. It supports complex data types and is designed to be highly performant for both reading and writing data. Avro files are often used for storing large datasets in a distributed manner.