The OMG Network consists of three components interacting together:
The OMG Smart Contracts
The Child Chain
PlasmaFramework Smart Contract
Deployed to the Ethereum network, the PlasmaFramework contract can be seen as a top-level contract containing other smart contract level functionalities, namely deposits, exits, and the receipt of blocks from the Childchain.
Run by the OMG Network, the Childchain application maintains the network state. It receives users' transactions and bundles them into blocks that are submitted to the PlasmaFramework contract.
Watcher application continuously monitors the Childchain – validating its behavior and reporting any inconsistency or malicious behavior to subscribed users. Watchers can be run by anyone. The bigger the number of running Watchers, the safer the network.