Cumulus
Cumulus clouds are shaped sort of like dots and are up in the air, like this project (as it is an initial prototype -- expect a rename when it gets cooler.)
Cumulus is an extension to Substrate that makes it easy to make any Substrate built runtime into a Polkadot compatible parachain.
Components
Cumulus Consensus
cumulus-consensus is a consensus engine for Substrate which follows a Polkadot relay chain. This will run a Polkadot node internally, and dictate to the client and synchronization algorithms which chain to follow, finalize, and treat as best.
Cumulus Runtime
A wrapper around Substrate runtimes to allow them to be validated by Polkadot validators and provide witness generating routines. It adds a validate_block API to the Substrate external interface which will be called by validators.
Integrating it into your substrate runtime will be as easy as importing the crate and adding this one line macro to your code.
runtime::register_validate_block!(Block, BlockExecutor);
Cumulus Collator
A planned Polkadot collator for a parachain.