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XCM enables different consensus systems to communicate with each other. Common cross-consensus use-cases include:

  • Sending tokens between blockchains
  • Locking assets on one blockchain in order to gain some benefit on a smart contract on another blockchain
  • Calling specific functions on another blockchain

These are just a few basic examples; once you can communicate with other consensus systems, you can create applications that can leverage multiple blockchains' capabilities. The potential it provides is especially evident in an ecosystem of highly specialized blockchains like Polkadot.

Decentralized distributed systems are very complex, so it's easy to make errors when building interactions between them. XCM is meant to be used by developers to package these interactions into their runtime logic before exposing that functionality to end users.

This chapter will cover what XCM is, what it isn't, and why it matters before exploring the different components that make up the XCM ecosystem.