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Advanced Topics


The EOS Core provides the basic building blocks for the system layer. However, since they are not implemented as smart contracts, they do not provide the same level of flexibility. Nevertheless, the core implementation is also open source, and thus it can be modified to suit custom business requirements.

The core protocols are:

  1. Consensus Protocol
  2. Transactions Protocol
  3. Network or Peer to Peer Protocol


The EOS blockchain is unique in that the features and characteristics of the blockchain built on it are flexible, that is, they can be changed or be modified completely to suit each business case requirement. Core blockchain features such as consensus, fee schedules, account creation and modification, token economics, block producer registration, voting, multi-sig, etc., are implemented inside smart contracts which are deployed on the blockchain built on the EOS blockchain. These smart contracts are referred to as system contracts and the layer as the EOS system layer, or simply the system layer.

The EOS Network Foundation implements and maintains these system contracts as reference implementations only, encapsulating the base functionality for an EOS-based blockchain. The system contracts are listed below:

  • eosio.bios - The eosio.bios contract is a special contract that is used to initialize the blockchain
  • eosio.system - The eosio.system contract is the core contract that implements the foundational EOS blockchain features
  • eosio.msig - The eosio.msig contract implements the multi-signature functionality
  • eosio.token - The eosio.token contract implements the system token functionality
  • eosio.wrap - The eosio.wrap contract implements a governance feature