Stratum
Stratum is a proposal for an open source client-server "overlay" protocol that enables thin clients. It is currently used by Electrum. While originally announced right before 2012[1], the protocol has not yet been completed and proposed as a BIP for standardisation.
Mining extensions
Main page: Stratum mining protocol
In addition to its use for bitcoin wallets, the stratum protocol is also in common use with mining extensions.
