If you attempt to save your Photoshop document as JPEG or JPG but it refused to save, you may need to change the image’s color mode. To change the color mode go to the top menu bar and press Image ...
The default Windows program for opening JPEG files is Windows Photo Viewer, which displays images without editing them. If you perform graphic design in your job, you should consider setting an image ...
You can convert a JFIF file to JPG, though the two formats are nearly identical, and most software will open a JFIF file as a JPG.