Effective REST API design involves mastering key principles to create intuitive and efficient interfaces that facilitate smooth system integration. Although REST is widely considered a standard for APIs, it is more of an art form that emphasizes consistency in design, which is crucial for ease of use. Consistent paradigms throughout an API, down to naming conventions, make it easier for developers to learn and adapt. REST APIs revolve around resources, which should be stable and clearly defined, with resource names being plural nouns to represent the pool of that resource type. Unique IDs and type fields are essential for identifying resources reliably and offering future flexibility. While hypermedia links (HATEOAS) are often considered the next level of REST, they are less practical in modern API consumption, though enabling users to traverse resources through stable links remains important. Adhering to standards such as those for JSON and HTTP is vital, particularly in the correct use of status codes and HTTP methods. Ultimately, building great APIs involves a focus on completeness and consistency across the API and with other APIs, ensuring developers have the tools to extend functionality beyond initial use-cases.