I will introduce Sereal and explain why we at Booking.com wrote it, and why we think it is superior to Storable in almost every scenario, including a discussion on "Storable upgrade-trap". As a follow up I will delve into the internals a bit, explain why it is fast and why it produces compact output suitable for the wire even without compression. I will also talk a little about how we at Booking.com use Sereal internally, and a bit about the possible future plans for the protocol.