It's a piece of code that can be executed in the blockchain

• Contract Account
  • field: Description
  • balance: Amount of ether this account owns
  • storage: Data storage for this contract
  • code: Raw machine code for this contract
  • only lives in an specific network
• External account:
  • i.e Metamask account
  • can be used to access the different networks
• A contract source is deployed to an specific network. The contract deployed is called an "instance" and live only there.