Quick answer: A PPTX file is the modern presentation file format for Microsoft PowerPoint. It's a ZIP archive of XML files that describe every slide, shape, text box, image, and note. Because it's editable, it's the format founders actually work in after a deck is generated.

The PPTX extension replaced the older PPT format in 2007 with the Office Open XML standard.

What's inside a PPTX

A .pptx file is a ZIP. If you unzip it, you'll see a predictable structure:

  • ppt/slides/slide1.xml, slide2.xml, and so on: each slide's shapes and text.
  • ppt/slideLayouts/ and ppt/slideMasters/: the templates and the master slides.
  • ppt/media/: the images embedded in the deck.
  • ppt/theme/: the colors and fonts.
  • ppt/notesSlides/: the speaker notes.

Because the content is text and shapes, every element can be moved, edited, and restyled in PowerPoint. That's the difference between a PPTX and an image of a slide.

PPTX vs PPT

  • PPT is the older binary format (1997–2003).
  • PPTX is the XML-based, smaller, safer modern format.

Anything produced today should be PPTX.

PPTX vs PDF

PPTX PDF
Editable Yes No, mostly
Purpose The working file The fixed share
Layout Rebuilds on other machines Fixed everywhere
Use case Editing, presenting Sending, archiving, printing

The PDF is the final read-only version; the PPTX is the file the founder rewrites for every meeting. The trade-offs are expanded in PPTX vs PDF.

PPTX vs Google Slides and Keynote

  • Google Slides imports PPTX, but some advanced formatting can shift.
  • Keynote opens PPTX and can export back to it.
  • PowerPoint is the reference implementation; the file is safest in PowerPoint.

Why "editable PPTX" matters for AI decks

Some AI presentation tools export the slides as locked images or as a proprietary canvas, or produce a PPTX where every slide is a picture. In that case the deck is editable in name only: you can't fix a word without redesigning the slide.

A genuine PPTX contains real text runs, shapes, and images. The slide text is selectable; the shapes can be moved; the file opens in PowerPoint without repair.

This is the reason Neatico writes native PPTX text runs, shapes, and images rather than flattened cards, and why it includes a repair step for phantom slide masters. The same thinking is in why the AI never touches a pixel coordinate and can AI make editable PowerPoint.

Fonts in PPTX

PowerPoint uses the fonts installed on the machine opening the file. If the deck uses a font that isn't installed, PowerPoint substitutes it and the layout shifts. The fonts for Chinese, Japanese, and Korean decks are handled separately (Microsoft YaHei, Yu Gothic, Malgun Gothic, SimSun).

Frequently asked questions

Can I open a PPTX without PowerPoint? Google Slides, Keynote, and LibreOffice all open it; some formatting may shift.

Why is my exported PPTX full of images? The generator flattened the slides to pictures. A true editable PPTX keeps text as text.

Can a PPTX be opened on a phone? The PowerPoint mobile app and the Office web viewer handle it.

What's the difference between PPTX and PPTM? PPTM supports macros; PPTX doesn't, and is the safe default.

Is a PPTX a good handover file? It is for working decks; the handover PDF handles the fixed presentation.

A PPTX is the working file, not the artifact. If the AI can hand you an editable slide rather than a picture, the deck is actually yours.

Related guide: the AI PowerPoint generator guide.