Terminology

You may have heard of one or multiple buzzwords thrown around in the cosmos and wider crypto ecosystem such shared security, interchain security, replicated security, cross chain validation, and mesh security. These terms will be clarified below, before diving into any introductions.

Shared Security

Shared security is a family of technologies that include optimistic rollups, zk-rollups, sharding and Interchain Security. Ie. any protocol or technology that can allow one blockchain to lend/share it's proof-of-stake security with another blockchain or off-chain process.

Interchain Security

Interchain Security is the Cosmos-specific category of Shared Security that uses IBC (Inter-Blockchain Communication), i.e. any shared security protocol built with IBC.

Replicated Security

A particular protocol/implementation of Interchain Security that fully replicates the security and decentralization of a validator set across multiple blockchains. Replicated security has also been referred to as "Cross Chain Validation" or "Interchain Security V1", a legacy term for the same protocol. That is, a "provider chain" such as the Cosmos Hub can share its exact validator set with multiple consumer chains by communicating changes in its validator set over IBC. Note this documentation is focused on explaining the concepts from replicated security.

Mesh security

A protocol built on IBC that allows delegators on a cosmos chain to re-delegate their stake to validators in another chain's own validator set, using the original chain's token (which remains bonded on the original chain). For a deeper exploration of mesh security, see Replicated vs. Mesh Security on the Informal Blog.