API

/krʊd/

n. “Create, Read, Update, Delete — the alphabet of persistent data.”

CRUD is an acronym representing the four fundamental operations that can be performed on persistent storage or resources in a database or application: Create, Read, Update, and Delete. These operations form the backbone of most software systems, allowing users and applications to manage data effectively.

In a REST context, CRUD operations map naturally to HTTP methods: POST for Create, GET for Read, PUT or PATCH for Update, and DELETE for Delete. This alignment simplifies API design and ensures that client-server interactions remain consistent and predictable.

For example, consider a CRUD interface for managing a contacts database. Create adds a new contact, Read retrieves contact details, Update modifies an existing contact’s information, and Delete removes a contact from the system. These four operations cover nearly all use cases for data management.

CRUD is not limited to relational databases; it applies to document stores, key-value stores, cloud services, and even local file systems. When combined with REST principles, CRUD provides a universal language for designing scalable and maintainable APIs.

Understanding CRUD is essential for developers, system architects, and anyone designing interactive applications. It provides a conceptual framework that ensures every data interaction has a clear purpose, promotes consistency, and reduces the likelihood of unintended side effects.

Many modern tools, frameworks, and platforms provide CRUD scaffolding or generators, allowing developers to quickly implement data management functionality while following best practices. Whether in web development, mobile apps, or enterprise systems, CRUD remains the fundamental model for interacting with data.

In short, CRUD is simple, pervasive, and indispensable: the unspoken grammar of data operations that powers everything from tiny scripts to massive cloud services.

/rɛst/

n. “Architect it once, call it anywhere.”

REST, short for Representational State Transfer, is an architectural style for designing networked applications. It emphasizes a stateless client-server communication model where resources are identified by URIs, and interactions are carried out using standard HTTP methods like GET, POST, PUT, PATCH, and DELETE.

In a RESTful system, each resource can be represented in multiple formats such as JSON, XML, or HTML. The server provides the representation, and the client manipulates it using HTTP verbs. REST is stateless: every request contains all information necessary for the server to process it, which improves scalability and simplifies reliability across distributed systems.

For example, a REST API might expose a resource at /users/123. A GET request retrieves the user, a PUT request updates the user, a PATCH request partially modifies the user, and a DELETE request removes the user.

REST is not a protocol or standard — it is a style of designing services. Constraints like uniform interfaces, stateless interactions, cacheable responses, layered system architecture, and code-on-demand (optional) guide developers to build simple, scalable, and flexible APIs. Adhering to these principles makes applications easier to maintain and allows clients written in different languages or platforms to interact seamlessly.

REST powers much of the modern web. Social media platforms, SaaS applications, cloud services like IaaS, PaaS, and microservices architectures often expose RESTful APIs. Its design encourages clear separation of concerns: the server manages resources, while the client handles presentation and state transitions.

Consider a developer building a dashboard that aggregates user data from multiple services. By leveraging REST APIs, they can fetch JSON representations from different servers, combine the data, and display a unified interface — all without needing specialized protocols or complex bindings.

While REST is widely used, alternatives like GraphQL or gRPC exist, offering different trade-offs in flexibility and efficiency. Nevertheless, REST remains a cornerstone of web architecture, emphasizing simplicity, statelessness, and universal compatibility through standardized HTTP mechanisms.