It's easy to convert images into PDF files -- whether on Windows, Mac, or directly on your mobile phone. We'll show you how it works.

Windows allows you to convert any image file with JPG, JPEG, PNG format to PDF without installing any third-party software via Windows Photos App.

Pick Save as PDF to choose a filename and destination, and you can even add password protection to the document if you want to. There's PDF functionality built right into Finder as well.

Step 2: Drag your PDF files into the "Merge PDFs" box or click the "Select Files" button to add files.

To convert a JPG file to a PDF file, simply change the file format on your computer's default photo-viewing app.

In the Preview app, for example, it's possible to create a single multi-page PDF document out of several separate image files.

Outlook 2013 supports the inclusion of JPG, GIF, PNG and BMP image files directly in a signature. To add a PDF image, you must include it as a Web link.