The four formats you will be saving your images you have edited in an image editing program in are:
PSD – Used for saving images that have layers. Save all your image files in this format. Once you save your file in a flat format such at PNG or JPEG you can never recover your lost layers.
TIFF – Used to save images for publication. I also save all the photos I scan in this format.
PNG – It supports a single layer with transparency. If you are going to embed a photo or graphic in a Word document or Google Doc, save it in this format.
JPEG – Does not support layers or transparency. This a good format for saving images that need to be compressed and shared online.