IN THIS CHAPTER
Back in the early days of the Internet, there was only text on the screen. In 1993, we first saw a graphical interface called Mosaic. It was based on HyperText Markup Language (HTML), which was a series of tags applied to the contents of the web page. In the case of text, the tags described the font, size, and color to be used, and where to start the text string. For graphics, the HTML tag included the name of the picture, its location in a folder, and its placement on the web page. The main point about HTML wasand still isthat it's a universal language. What you see on your screen as you design a page is pretty much identical to what a viewer on a different computer system and perhaps halfway around the world sees. Today, there are at least a half a dozen different browsers in use, and they all interpret HTML the same way.
HTML is good for more than just display specifications. You can also use it to create moving graphics, animations, and rollover buttons that change state when they see a mouse. (But so did my Aunt Hilda….) It's the ability to maintain transparencies, and therefore to build a graphic in layers, that makes these tricks possible.
You can also create some very interesting images that change when you click and hold the mouse button. They're done by dividing the picture into slices. You explore this a bit further along in the chapter, because you need to understand how to work with transparent images and GIF layers first.