Pinning

From the IPFS docs:

Pinning is the mechanism that allows you to tell IPFS to always keep a given object somewhere — the default being your local node, though this can be different if you use a third-party remote pinning service.

On estuary, pinning is effectively done by the doPinning function on pinning.go. doPinning checks the pinning list and pins content on the estuary IPFS node, then it updates the ToCheck channel, which is a queue used by replication.go to make deals for new contents. Eventually, every content on Estuary is pinned, most often by calling pinContent (pinning.go) which is a function that feeds new content to the pinning queue, content that is later consumed by doPinning.