Several open boxes, some having kittens in them.
'In fact, the mere act of opening the box will determine the state of the cat, although in this case there were three determinate states the cat could be in: these being Alive, Dead, and Bloody Furious.' - Terry Prachett, Lords and Ladies
Efficient binary serialization format. Cross-platform. Faster and smaller than JSON.
List of supported datatypes: integer, boolean, nil, float, string, binary, array, map, extension (tuple of data, defined by the application).
Smaller file sizes are better for mobile and IoT. It's designed for efficient over the wire transmission. Image shows a minimal JSON blob being 27 bytes and the equivalent MessagePack being 18 bytes.
Can handle fuzzy data shapes. Supports static-typing. Support for streaming deserializers. Official language support is great! List of supported languages: C, C++, C#, D, Erlang, Go, Haskell, Java, Javascript, Lua, OCaml, Perl, PHP, Python, Ruby, Scala, Smalltalk, Swift, etc...
Let's go herd some cats... To the code-mobile!! Image shows lots of cats being lazy and cute on the sidewalk.