What is the name of Google's method for serializing structured data?

Google's method for serializing structured data is Protocol Buffers, also called protobuf.

Protocol Buffers is a language-neutral, platform-neutral format for encoding structured information into a compact binary representation. A developer defines the data's fields and types in a .proto schema, then runs Google's protoc compiler to generate source code for supported programming languages. Applications can serialize objects into protobuf messages and later parse them reliably.

Google created protobuf for internal use because it wanted data that was smaller and faster to process than XML. Explicit field numbers and schema rules also make it possible to add fields while preserving compatibility with older software, provided the original field numbers are not carelessly reused.

Protocol Buffers became an open-source technology and is widely used in Google's systems for storing and exchanging structured data. It also underpins many remote-procedure-call systems, including gRPC. Avro, XML, and JSON can also represent structured data, but they are different formats or technologies rather than names for Google's protobuf method.