What are File Extensions?

File extensions are the suffixes at the end of filenames (like .json, .csv, .jpg) that tell your operating system and applications what type of file it is and how to open it.

Common Examples

• .json — JavaScript Object Notation data
• .csv — Comma-separated values table
• .xml — Extensible Markup Language
• .txt — Plain text

Why They Matter

• Help the OS choose the correct default application
• Inform users about file content at a glance
• Enable correct handling by scripts and programs