There are two main entities in Elrond: users and nodes. Users, each holding a (finite) number of public / private (Pk/sk) key pairs (e.g. in one or multiple wallet apps), use the Elrond network to deploy signed transactions for value transfers or smart contracts' execution. They can be identified by one of their account addresses (derived from the public key). The nodes are represented by the devices that form the Elrond network and can be passive or actively engaged in processing tasks. Eligible validators are active participants in Elrond's network. Specifically, they are responsible for running consensus, adding blocks, maintaining the state and being rewarded for their contribution. Each eligible validator can be uniquely identified by a public key constructed through a derivation of the address that staked the necessary amount and the node id. Relations between entities in the Elrond protocol are shown in the figure below.