Ripple

Ripple is older than bitcoin. It started in 2004 as RipplePay[1].

The Ripple company[2] was founded in 2012 as OpenCoin, later renamed to Ripple. There was already an OpenCoin project earlier that is about digital chash but has nothing to do with Ripple.

Ripple is used to exchange value fast and borderless. It enables banks to bypass intermediaries and clearing houses.

The Ripple network is permissioned, the validating nodes are known and do have to trust each other. This eliminates the need of things as Proof of work (energy saving) and all kind of checks (speed). Nodes have a validator list of nodes they trust. There most be sufficient overlap in the validator lists of nodes to ensure they keep do not come to different conclusions. So when the network grows not every node needs to have all other nodes in the validator list as long as the overlap is OK.

Chalenges

As 2 nodes that are needed to do a value exchange do not need to be in the same network (have each other in the validator-list) there can be time an consequently value differences between the nodes. This can be exploited.