Lección 1
What Is JSON? en español
Guía en español para json what is json: Definition, history, and where JSON appears in modern software.
Este contenido todavía no está disponible en español. Se muestra la versión en English mientras completamos la localización.
JSON stands for JavaScript Object Notation. Despite the name, JSON is a text-based data format, not a programming language. Any environment with a JSON parser can read and write it—Python, Java, Go, Rust, and countless others.
A minimal example
{
"name": "Ada",
"active": true,
"score": 98.5
}
This document describes one object with three properties: a string, a boolean, and a number.
Why JSON became popular
Before JSON dominated web APIs, XML was common. JSON is usually shorter and easier for humans to scan, while still being machine-readable. It maps naturally to objects and arrays in most programming languages.
Today you will find JSON in:
- REST and GraphQL API request and response bodies
- Configuration files for tools, CI pipelines, and cloud services
- NoSQL databases that store documents
- Log and event streams structured for analysis
JSON vs JavaScript object literals
JavaScript code can look similar to JSON, but they are not the same:
| Feature | JSON | JavaScript object |
|---|---|---|
| Keys | Must be double-quoted strings | Can be unquoted identifiers |
| Trailing commas | Not allowed | Often allowed |
| Comments | Not allowed | // and /* */ allowed |
Functions, undefined | Not allowed | Allowed |
Copying JavaScript object syntax into a JSON-only system is a frequent source of parse errors. The rest of this course explains the rules JSON enforces.
Key takeaway
JSON is a strict, portable way to represent structured data as text. Learning its rules helps you read APIs, write configs, and debug invalid payloads confidently.