When working with files that have been scanned or created in an application such as Adobe Photoshop, the most commonly used format will be a .tiff file. A .tiff won’t compress the file as much as a .jpeg (or .jpg) but it will take up more storage space. Jpeg files are more compressed files and are generally used to email images or to keep digital camera files, and can be used for the web along with .gif and .png format. PDF stands for portable document format, this is a universal format which can be used for text and image files. EPS, PSD, AI, INDD etc are formats that refer to the application program they were created in.
Therefore, .tif or .pdf are the best file formats when saving work for printing; .jpg, .gif or .png are best when saving work for email or websites.