F1: Data Storage and Interchange
At Google, Protocol Buffers are ubiquitous for data storage and interchange between applications. When we still had a MySQL schema, users often had to write tedious and error-prone transformations between database rows and in-memory data structures. Putting protocol buers in the schema removes this impedance mismatch and gives users a universal data structure they can use both in the database and in application code.
BSON is another alternative in the data storage and interchange space, with MongoDB benefiting from BSON in a similar way to F1 benefiting from Protocol Buffers. The F1 usage of protocol buffers as column types, and the query ability is extremely nice.