1. Introduction

In this tutorial, our primary goal is to build a RESTful API using Go, the statically typed, compiled language that's renowned for its simplicity, efficiency, and ease of use. We'll be focusing on creating a basic CRUD (Create, Read, Update, Delete) API, which will allow us to understand the fundamental principles of REST architecture and its implementation in Go.

By the end of this tutorial, you will learn:
- The basic principles of REST architecture
- How to implement RESTful APIs using Go
- How to handle HTTP requests and responses in Go

Prerequisites:
- Basic knowledge of programming principles
- Familiarity with Go language syntax
- Go installed on your machine

2. Step-by-Step Guide

2.1 Setting Up Your Go Environment

Before we can start building our API, we need to set up our Go environment. You can download and install Go from the official website. Once installed, create a new directory for our project.

2.2 Creating Our First Endpoint

A RESTful API is all about handling HTTP requests at various endpoints. Let's create a basic 'Hello, World!' endpoint.

package main

import (
    "fmt"
    "net/http"
)

func helloWorld(w http.ResponseWriter, r *http.Request){
    fmt.Fprintf(w, "Hello, world!")
}

func main() {
    http.HandleFunc("/", helloWorld)
    http.ListenAndServe(":8080", nil)
}

In this code snippet, we're importing the necessary packages, creating a function helloWorld to handle HTTP requests, and starting a server on port 8080.

3. Code Examples

3.1 Creating the CRUD API

Let's create a simple API for managing a list of books. We'll start by defining our book struct and a slice to represent our 'database'.

type Book struct {
    ID     string  `json:"id"`
    Title  string  `json:"title"`
    Author string  `json:"author"`
    Year   string  `json:"year"`
}

var books []Book

3.2 Implementing the CRUD Operations

Next, we'll implement the CRUD operations. We'll create functions for getting all books, getting a single book, creating a book, updating a book, and deleting a book.

func getBooks(w http.ResponseWriter, r *http.Request) { /*...*/ }

func getBook(w http.ResponseWriter, r *http.Request) { /*...*/ }

func createBook(w http.ResponseWriter, r *http.Request) { /*...*/ }

func updateBook(w http.ResponseWriter, r *http.Request) { /*...*/ }

func deleteBook(w http.ResponseWriter, r *http.Request) { /*...*/ }

Each function will process HTTP requests, perform the necessary operations, and return HTTP responses.

4. Summary

This tutorial covered the basics of building RESTful APIs in Go. We discussed REST principles and how to implement them using Go's http package.

For further learning, consider exploring more complex data structures, adding authentication to your API, or deploying your API to a server.

5. Practice Exercises

1. Extend the book API to include a 'Publisher' field.
2. Create a new API for managing a list of users, with fields for 'Name', 'Email', 'Password', and 'DateRegistered'.
3. Add a 'BooksBorrowed' field to the user struct, and create an endpoint for borrowing a book.

Remember, the best way to learn is by doing. Happy coding!