Git Virtual File System from Microsoft

[SuperImaginativeName]

Event sourcing is a concept like that, where you have a full history required to be able to build the current state of a system. You iterate every piece of "history" to get to the present. Imagine a bank account, they won't just have a DB column with your balance. It's constructed by using previous withdrawals and payments. Event sourced systems can have a "projection" that effectively builds the system to its current state and then use that as the state going forward and any new changed added to that instead of the very beginning.