As introduced earlier in this chapter, we are building a simple Java application using web3j. Let's understand briefly the mechanics behind this API.

Web3j is the Java port of Ethereum's web3 API, which manages communication (JSON-RPC) between Ethereum clients and the network. For each smart contract, web3j generates a wrapper class, simplifying the access and smart contract interaction with Ethereum. Thus, all complexities will be hidden and you will not be forced to initiate RPC calls on your own. The following diagram (from the official documentation) depicts the interaction flow between web3j and Ethereum: