AVRO is a data serialization framework developed within the Apache software foundation. It allows for the efficient storage and transmission of data in a compact binary format, making it suitable for big data applications. AVRO uses a schema to define the structure of the data, which helps ensure compatibility and enables easy data evolution over time. One of the key features of AVRO is its support for dynamic typing, meaning that the data can be read and written without requiring a predefined schema. This flexibility makes AVRO particularly useful in environments where data structures may change frequently, such as in Hadoop ecosystems.