A file format that lets you specify certain object properties without needing to know any code. Most Frameworks use Json files.
Json files can be read in almost any text editing program, however, one made specifically for reading code like Notepad++ or Visual Studio will offer options for color-coding, bracket matching, and many other useful features.
Official site: https://www.json.org/json-en.html
Utility to check formatting: https://smapi.io/json