Over the years, Adobe's PDF file type has become a universally accepted method for sharing digital documents. The format's cross-platform adoption means the documents can be viewed on almost any mobile device or computer, so it's no surprise to find that macOS includes native support for viewing and creating PDF files.
In the Preview app, for example, it's possible to create a single multi-page PDF document out of several separate image files. The feature is particularly useful if you need to share a number of scanned documents over email or digitize something for reference. Keep reading to learn how it's done.
Right-click (or Ctrl-click) one of the highlighted files and select Open With -> Preview in the contextual dropdown menu.
In Preview's sidebar, drag the thumbnail images into the order that you want them to appear in the PDF document. Use the Rotate button in Preview's toolbar to change the orientation of individual pages (drag a selection over multiple pages to rotate several at once).
Click Show Details to expand the Print dialog and browse the full set of options. Make sure the All button is selected in the Pages options. Note that you can double-check the orientation of each image by clicking the arrows below the print preview, and use the Orientation buttons to correct any if required.
Select Save as PDF from the PDF dropdown menu in the lower left of the Print dialog.
The Save dialog will appear. Give your new PDF a name and choose a save location. Fill in the Title, Author, Subject, and Keywords fields if desired (these details are searchable in Spotlight). The Security Options. button also lets you optionally set a password to open the document, copy from it, and/or print it.
Note that the Save as PDF option can be accessed from the Print dialog window within a number of macOS apps, not just Preview. You can use it to create PDFs of web pages viewed in Safari, or Word documents opened in Pages, for example.