JPG (pronounced, Jay peg) is a file format used for storing and displaying images. It’s the most common format online, only really challenged by GIF.

JPG is the acronym for Joint Photographic Experts Group. It has the apparent disadvantage that when you save a picture in the format it loses some data. This is caused by JPGs compressing the image, which may seem a major drawback. However, the format does preserve a lot of information even in high compressions which makes it ideal for screen viewing.

Most digital cameras save images by default as JPGs. In most case though, you do have some choice over the degree of compression used.

Even inexpensive point-and-shoots will have a menu giving a choice of picture quality in their armory. Please note, this is not about “resolution” which measures the number of pixels in the image. The image quality you set determines by how much the picture will be compressed, so how much quality is lost.

There is a further trade-off in that the higher the quality, the more space the picture will take on your memory card. Remember, you can always use another memory card, but you can never recover the loss of quality in the image.

The bottom line is the use you intend for the final picture. Web pages and emails are best served by low quality pictures. Making prints from the image requires the highest quality obtainable at source.