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Many projects and tokens are deployed on several chains at once. How each chain's copy came about, who issued it, and whether the totals add up is where multichain projects most often go wrong.

Some projects would rather not share a public chain with everyone else, so they build a chain of their own (an app-chain). They set their own performance and rules, and in exchange carry their own security, validators and bridges.

Bitcoin itself does one thing: record who owns how much BTC. The Lightning Network, inscriptions and runes, wrapped BTC, BTC staking and assorted "Bitcoin Layer 2s" that have grown up around it make up the Bitcoin ecosystem.

Cosmos is not one chain but a chain-building kit (the Cosmos SDK plus CometBFT consensus) and a chain-to-chain communication protocol (IBC). The dozens of chains built with it are known collectively as the Cosmos ecosystem.