System contracts, system accounts, privileged accounts

At the genesis of the EOS blockchain, there was only one account present, eosio account, which was and still is the main system account. During the EOS blockchain bootstrap process other system accounts, were created by eosio account, which control specific actions of the system contracts. You can see them listed in the About System Contract section.

Note the terms system contract and system account. Privileged accounts are accounts which can execute a transaction while skipping the standard authorization check. To ensure that this is not a security hole, the permission authority over these accounts is granted to eosio.prods system account.

As you just learned the relation between a system account and a system contract, it is also important to remember that not all system accounts contain a system contract, but each system account has important roles in the blockchain functionality, as follows:

Account	Privileged	Has contract	Description
eosio	Yes	It contains the eosio.system contract	The main system account on the EOS blockchain.
eosio.msig	Yes	It contains the eosio.msig contract	Allows the signing of a multi-sig transaction proposal for later execution if all required parties sign the proposal before the expiration time.
eosio.wrap	Yes	It contains the eosio.wrap contract.	Simplifies block producer superuser actions by making them more readable and easier to audit.
eosio.token	No	It contains the eosio.token contract.	Defines the structures and actions allowing users to create, issue, and manage tokens on the EOS blockchain.
eosio.names	No	No	The account which is holding funds from namespace auctions.
eosio.bpay	No	No	The account that pays the block producers for producing blocks. It assigns 0.25% of the inflation based on the amount of blocks a block producer created in the last 24 hours.
eosio.prods	No	No	The account representing the union of all current active block producers permissions.
eosio.ram	No	No	The account that keeps track of the EOS balances based on users actions of buying or selling RAM.
eosio.ramfee	No	No	The account that keeps track of the fees collected from users RAM trading actions: 0.5% from the value of each trade goes into this account.
eosio.saving	No	No	The account which holds the 4% of network inflation.
eosio.stake	No	No	The account that keeps track of all EOS tokens which have been staked for voting.
eosio.vpay	No	No	The account that pays the block producers accordingly with the votes won. It assigns 0.75% of inflation based on the amount of votes a block producer won in the last 24 hours.
eosio.rex	No	No	The account that keeps track of fees and balances resulted from REX related actions execution.