Origin
PDF was created by Adobe to solve a document problem: a page should look the same when opened on a different machine, printed on a different device, or archived for later. That made it central to publishing, forms, manuals, contracts, and scanned document workflows.
Images are part of PDF, but PDF is larger than images. A page can contain JPEG-compressed photos, lossless images, vector paths, selectable text, fonts, annotations, metadata, and color-management information.
Technical characteristics
A PDF describes pages. Raster images inside those pages may be compressed in different ways, and text can remain text instead of becoming pixels. That is why a clean PDF scan with OCR can be searchable, selectable, and much more useful than a folder of flat screenshots.
The same flexibility can create confusion. A PDF may be tiny because it contains vectors and text, or huge because it embeds high-resolution scans. It may be perfect for printing or poor for extraction depending on how it was made.
Where it fits
Use PDF when order, pagination, annotation, or document exchange matters: receipts, forms, reports, slide exports, scanned packets, and image sets that need to travel as one file. Use JPG, PNG, WebP, or AVIF when the object is just a single image for a page or app.
A practical rule: convert images to PDF when you need a document; convert PDF pages to images when you need pixels.
Best uses
- Multi-page image documents
- Forms, receipts, and records
- Print or review workflows
Use another format when
- Single web images
- Responsive photo galleries
- Cases where users need raw editable pixels