拡張子

1. Origins, structure, and basic meaning

• Structure: 拡張子 is read as かくちょうし and is an information-technology noun for a file extension, linked to a file type in 画像ファイルの拡張子.
• Basic usage: It is used when checking a file before sending it or when an incorrect extension change may prevent the file from opening.

2. Common pitfalls and similar expressions

• Possession
  • Identify the file with の, as in ファイルの拡張子.
• Changing it
  • The example warns that changing 拡張子 incorrectly can prevent the file from opening.