nodeos(node + EOSIO = nodeos): the core EOSIO node daemon that can be configured with plugins to run a node. Example uses are block production, dedicated API endpoints, and local development.
cleos(CLI + EOSIO = cleos): the command line interface to interact with the blockchain and to manage wallets.
keosd(key + EOSIO = keosd): the component that securely stores EOSIO keys in wallets.
EOSIO.CDT: toolchain for WebAssembly (Wasm) and a set of tools to facilitate smart contract writing for the EOSIO platform.
cleosis a command line tool that interfaces with the REST APIs exposed by
nodeos. You can also use
cleosto deploy and test EOSIO smart contracts.
keosdis a key manager daemon for storing private keys and signing digital messages.
keosdprovides a secure key storage medium for keys to be encrypted in the associated wallet file. The
keosddaemon also defines a secure enclave for signing transaction created by
cleosor a third party library.
keosdcan be accessed using the wallet API, but it is important to note that the intended usage is for local light client applications.
keosdis not for cross network access by web applications trying to access users' wallets.