Images are ignored by non-graphical browsers. If the browser does not recognize an image it may put up very large distracting squares onto the Web page instead of the image. Images which are very large take a long time to download on the Web and users trying to view your page will probably leave before your large image has completely downloaded. These topics about what graphic software can do are beyond the realm of this tutorial. Cute little drawings and animations are .gif file images.
Photographs are usually .jpg file images.
Many logos are .jpg images. Only the .gif images can have a transparent background. An icon with a transparent background will not have a white, black, or colored block that appears on a textured web page behind the image. See the article Web Images, Intro. which lists many types of image files. There is no end tag for the image code.