.jpg  or JPEG files are the most common digital image file format. JPEG’s can display millions of colors which makes them great for photographs. Imagine a picture of a sunset where the colors in the sky range from bright yellow through dozens of different levels of orange. If the digital image file couldn't support millions of colors, it wouldn't be able to capture the many different shades of orange in the sunset. 

JPEG's use digital compression to keep file size small. Small file size is a good thing, as huge files take up lots of hard drive space and are slow to move or copy. But the digital compression used by JPEG's is lossy. That means each time you open a JPEG file and edit in some way then resave it, some of the image quality is lost. This does not apply to copying or moving the file. It only applies to opening the file in an image editing program, changing it in some way, and re-saving it.

.gif files are another common type of image file. GIF files are limited to 256 colors, so they would not work well for photographs. They are designed for clip art would use a very limited color palette. GIF files are extremely small.

 

.bmp or bitmap is a file format created by Microsoft and works well with any type of graphic. The file size is generally larger than a JPEG.

.pic or .pict is a file format created by Apple and works well with any type of graphic.

 
If you want to change a digital image file from one type to another, search the Internet for a file conversion website using the search terms “digital image file converter.”