The application layer

The fifth and final (top) layer of the stack is called the application layer. This layer deals with providing the interfaces to access, program, and use the blockchain. The following diagram shows the common capabilities that are part of this layer:

The application layer includes capabilities that provide application interfaces on top of the blockchain, both out-of-the-box functionality and custom implementations. The capabilities describe how the digital ledger is implemented and exposed to the world, how smart contracts can be built and run on the blockchain, and how third-party applications can interact with the digital ledger and smart contracts.