Node: Some process that is able to store data, do processing and communicate with other nodes.
Peer: The other nodes that a peer is connected to.
Peer-to-peer (P2P): Protocols where resources are divided among multiple peers, without the need of central coordination.
Device: A node capable of storing some data locally.
Identity: A user's cryptographic identity, usually a single or several public keypairs.
User: A (human) end-user that may have multiple devices, and some form of identity.
Data replication: Storing the same piece of data in multiple locations, in order to improve availability and performance.
Data sync: Achieving consistency among a set of nodes storing data
Mobile-friendly: Multiple factors that together make a solution suitable for mobile. These are things such as dealing with mostly-offline scenarios, network churn, limited resources (such as bandwidth, battery, storage or compute).
Replication object: Also known as the minimal unit of replication, the thing that we are replicating.
Friend-to-friend network (F2F): A private P2P network where there are only connections between mutually trusted peers.
Content addressable storage (CAS): Storing information such that it can be retrieved by its content, not its location. Commonly performed by the use of cryptographic hash functions.
Public P2P: Open network where peers can connect to each other.
Structured P2P network: A public p2p network where data placement is related to the network topology. E.g. a DHT.
Unstructed P2P network: A public p2p network where peers connect in an ad hoc manner, and a peer only knows its neighbors, not what they have.
Super-peer P2P network: A non-pure p2p network, hybrid client/server architecture, where certain peers do more work.
Private P2P: Private network where peers must mutually trust each other before connecting, can either be F2F or group-based.
Group-based P2P network: A private p2p network where you need some form of access to join, but within group you can connect to new peers, e.g. friend of a friend or a private BT tracker.