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CrowsForge
Module 3~8 min

File Types and Extensions

The letters after the dot in a file name, like .pdf or .jpg, tell the computer what kind of file it is.

What You'll Learn

  • What a file extension is
  • Common file extensions and what they mean
  • Why file types matter

What Is a File Extension?

A file extension is a short suffix at the end of a file name that indicates the file's type or format. The operating system uses it to decide which program should open the file.

Common Examples

Some common extensions include .docx for documents, .jpg or .png for images, .mp3 for audio, and .pdf for portable documents.

Example

Double-clicking a .jpg file usually opens a photo viewer, while double-clicking a .docx file usually opens a word processor -- the extension tells the operating system which program to use.

Key Concepts

File ExtensionFile Format.pdf / .jpg / .docx

Key Takeaways

  • A file extension indicates the file's type or format
  • The operating system uses extensions to choose the right program
  • Common extensions include .pdf, .jpg, and .docx

Knowledge Check

What does a file extension typically indicate?

What does a file extension typically indicate?