You may have encountered some or all of the file types below. They’re all examples of plain text files. If your Finder (macOS) or File Explorer (Windows) displays file extensions, these file types will each show the corresponding two- or three-letter extension at the end of the file name. For example: myfile.txt or myfile.xml.
- txt (= text)
- csv (= comma separated values)
- tsv (= tab separated values)
- html (= hypertext markup language)
- xml (= extensible markup language)
- css (= cascading style sheet)
- md (= markdown)
- json (= javascript object notation)
- py (= python script)
- sh (= shell script)
- svg (= scalar vector graphic)
- ics, ical (= calendar file)
Most folks have no reason to interact directly with most of these file types. Double-clicking a file with the .ics extension at the end, which may have come to you as an email attachment, will likely open your default calendar application and add an event to it. Double-clicking a file with the .html extension at the end, as previously mentioned, will likely open your default browser and display a web page formatted according to the instructions in the file. Double-clicking a file with the .csv extension will likely open your default spreadsheet application (probably Excel) and display the file contents as data organized in rows and columns.
By contrast, the file types below are not written in plain text.
- docx (= Word document)
- xlsx (= Excel document)
- pptx (= PowerPoint document)
- jpeg, png, webp (= image files)
- pdf (= portable document format)
- rtf (= rich text format)