JPEG stands for Joint Photographic Experts Group. It was a format designed for saving photographic images on digital cameras. PNG stands for Portable Network Graphics. It was a format designed by Chris Lilley of the W3C, the people who make HTML, CSS and javascript, and was designed as the ideal image format for the web. Now it's one thing if you consider size a big issue when saving images to a digital camera, but on the web the difference between a JPG and a PNG in size isn't worth the loss in quality inherent in saving to a lossy format. PNG is designed for the web, JPEG isn't. Don't listen to advice from questionable sources without information to back up why. And please go check wikipedia for yourself and get a thorough understanding of all the formats you use and when to use them - they all have their advantages and disadvantages. You wouldn't use one screwdriver for all tasks, formats are the same thing.