If you are just beginning your journey into the world of Web3 development, you may have come across terms such as "RPC" and "API" and wondered what these words mean. Here is an explanation of what each of these terms signify, how they are related, and the differences between them. Additionally, you will get a better understanding of the role these concepts play in the Web3 development world. Let's begin!

RPC vs. API

Let's start by examining what Remote Procedure Call (RPC) is. It is a protocol that allows one computer or program to communicate with another computer or program from a distance. In basic terms, it allows you to access a network.

The client must begin the process by sending a message to a remote server. Upon receiving the message, the server will respond, after which the client will resume its original process.

API stands for Application Programming Interface, which allows one computer or system to communicate with other computers or programs over a shared network. Once connected to the network, APIs make it possible for the devices to interact with each other.

It is common to hear people using the terms RPCs and APIs interchangeably, but they are different. APIs provide the basis for two machines to interact on a network, allowing for data to be passed between them. RPCs are the calls made between the two computers, where the API provides guidance on how to use the calls effectively.

The main difference between RPCs and APIs is that RPCs link you to a network while APIs allow you to interact with other machines on the network.

An Example of RPCs and APIs

An example can help to demonstrate the subtle difference between RPCs and APIs. RPCs connect to a network and APIs interact with other computers or programs on that network. Essentially, RPCs are local while APIs are communicative.

Let's take a look at another case. Suppose you sent your mom an email to ask her to make some cookies for you. This can be thought of as an RPC. You (the customer) sent a request for cookies to your mom (the server). Your mom does the necessary baking, and then sends you the cookies to fulfill your request.

If you choose to get a pizza and your mom doesn't have the ingredients, you must go to a pizzeria. Just like when you go to the pizzeria, you don't have access to the kitchen ingredients, but you can place an order. The menu provides the pizzas available for ordering along with the toppings and other options you can choose from. This is an example of an application programming interface (API).

An RPC is a specific request for information on the blockchain, whereas an API is like a framework for complex communication.

RPCs and APIs in Blockchain

In order to communicate with blockchain networks, Web3 developers need to use either Remote Procedure Calls (RPCs) or Application Programming Interfaces (APIs). These are tools that allow developers to remotely connect to existing blockchain nodes, rather than having to set up and operate their own nodes.

In both Web2 and Web3 contexts, the relationship between RPCs and APIs remains similar, differing only in the underlying infrastructure. Specifically, RPCs provide the connectivity to a blockchain network, while APIs allow for interaction with other nodes on the network.

RPCs allow Web3 developers to communicate with distant blockchain nodes by sending data requests. As an example, Web3 wallets can utilize an RPC endpoint to request information from blockchain nodes.

RPCs can be used to query the blockchain for the information required to answer questions such as 'how many X tokens are in Y wallet?' and 'does this user have enough X tokens to cover the gas fee for this transaction?'.

If you need to write and read information to the blockchain, a full API that allows for the exchange of data between nodes in the network will be required. When you use a DEX to swap cryptocurrencies in your wallet, for example, you must write data to the blockchain with the updated balance. Additionally, APIs will be necessary if you're constructing a dApp which is constantly communicating with blockchain networks, not merely requesting data.