In computer science, a literal is a textual representation (notation) of a value as it is written in source code.
[1][2] Almost all programming languages have notations for atomic values such as integers, floating-point numbers, and strings, and usually for Booleans and characters; some also have notations for elements of enumerated types and compound values such as arrays, records, and objects.
In some object-oriented languages (like ECMAScript), objects can also be represented by literals.
The JSON data interchange format is based on a subset of the JavaScript object literal syntax, with some additional restrictions (among them requiring all keys to be quoted, and disallowing functions and everything else except data literals).
Because of this, almost every valid JSON document (except for some subtleties with escaping) is also valid JavaScript code, a fact exploited in the JSONP technique.