JSON (JavaScript Object Notation) is a lightweight data-interchange format that is easy for humans to read and write and easy for machines to parse and generate. JSON is text-based and uses a syntax that is familiar to programmers who use JavaScript, although it is language-independent. It represents data structures in a simple, hierarchical manner using key-value pairs and arrays. JSON is widely used for transmitting data between a server and a client in web applications, APIs, and configurations. Its simplicity and ease of use make it a preferred format for data exchange in modern web development.