Avro is a remote procedure call and serialization framework developed within Apache's Hadoop project. It uses JSON for defining data types and protocols, and serializes data in a compact binary format. Its primary use is in Apache Hadoop, where it can provide both a serialization format for persistent data, and a wire format for communication between Hadoop nodes, and from client programs to the Hadoop services.
It is similar to Thrift, but does not require running a code-generation program when a schema changes (unless desired for statically-typed languages).
‒ Courtesy of Wikipedia
There are currently 3 groups being archived from Avro (avro.apache.org).