General HTML

This document is an introduction to the hypertext language HTML, and some of its uses. As mentioned earlier, HTML is an acronym for HyperText Markup Language. HTML is a collection of commands written in text format to create documents such as this one.

One advantage to writing documents in HTML format is that they can be viewed on the most advanced level of the Internet, the World Wide Web. The World Wide Web is often abbreviated as WWW, or W3, or the Web. A document written in HTML and then put on a server accessible to the Internet can be viewed by anyone who has access to the Internet and a Web Browser. A Web Browser is a software program used to view HTML documents. If reading this document via computer, a browser is being used. There are several different browser programs available such as MacWeb, Mosaic, and Netscape. All of these browsers can perform the same basic operations, but to simplify matters we will assume use of the Netscape Browser and will be mentioning different buttons to click on in Netscape.

Images and Text

Besides formating documents, HTML allows easy inclusion of images into documents. The following example shows how images can be easily included along text.

The Pythagorean Theorem: Given any right triangle, the hypotenuse side squared equals the sum of each of the legs squared.

Images can be more intricate then a simple sketch. For instance here is a M C Escher print titled Day and Night.

Of course the more intricate an image is, the longer it takes the browser to download and view the document. Viewing large images can take an especially long time if the original document is on the Internet instead of a local machine. Also the more intricate the image, the more memory needed to store the image on the hard drive.

Links to Other Documents

Not only can images be included in a HTML document, but also connections to other hypertext documents, called a hyperlink or link can be included. To move from one document to another document, simply click once on the underlined or colored text. These documents can either be files on the machine being used, or documents on the Web.

For instance, below are links to other documents within this package. By clicking once on any of the highlighted text links, a new document will appear in the browser window.

Before accessing any of these documents, there are a few browser commands to know. To return to the previously viewed document after moving forward via a hyperlink, click on the Back button in the upper left-hand corner. To stop the downloading of a new document, click on the Stop button in the upper right-hand corner. The Stop button is especially useful if Netscape is taking a long time to download the document.

If the browser program being used is connected to the Internet, other HTML documents around the world can be viewed. Here are some links to Internet cites online. If the browser is not online, an error message may appear. It is also possible that some of links below may not work due to some part of the system being down.

Using Links for Mathematics

Another advantage of using HTML is that it allows the writer to explain at different levels of understanding. For instance, below is a link to a first year calculus theorem and its proof called the Fixed Point theorem. Two types of links are contained in the example. First, mathematical terms and theorems have hyperlinks to their definitions. Second, at the end of some sentences in the proof there are links to more detailed justifications. Remember to return to this document, General HTML, click on the Back button on the Netscape browser's preference panel.

Notice that using hypertext for writing the proof opens the text to a wider audience. A person conversant in calculus can read the theorem and proof as is to refresh their memory, while a beginning calculus student can quickly reference unknown terms or further explanations to parts of the proof.

Media Beyond Images

Another advantage of HTML documents is its ability to manipulate media beside images. Provided that one has other supporting software available, an HTML document can include links to sounds and movies. For instance if one has an MPEG viewer, a software program that can view MPEG movies, the following movie can be seen of an icosahedron deforming into a dodecahedron. If the machine being used does not have an MPEG viewing program, or if the Netscape Browser has not been configured to call up a MPEG viewer, a prompt will appear asking if the file should be saved to a disk or if a viewer should be configured. For now, if this prompt appears, click on the cancel transmission option.

Similarly, one can include sound files that can be heard by using a sound software program, again provided that software is available on the machine and that the machine has speakers!

Other Links

HTML has been written so that one can produce links to not only documents, images, and other media, but also links to files for other programs. For instance, one could include a link to a file for a dynamic geometry software such as Cabrí, Geometer's Sketchpad, or The Geometric Supposer. Below is an example of a link to a Geometer's Sketchpad file. If the Sketchpad program is in the machine and the Browser is properly configured, when the user clicks on the link to the Sketchpad file, the Sketchpad program will come up with the downloaded sketch. Similarly, links to Mathematica worksheets, Excel spreadsheets or any other type of file can be made which the viewer can use and manipulate provided the application software is available.


Creating documents in HTML has many advantages over other types of electronic text, not to mention standard printed text. HTML documents can be easily viewed by anyone with access to the Web on any machine, be it a PC, Mac, or Workstation. HTML documents also allow simple inclusion of images along with text, not to mention the potential to include sound and images. Writing documents in HTML enables the writer to express information at many different levels of the reader's understanding. Because of these benefits, HTML documents are a powerful tool for expressing information in today's computer age.

To view the other hypertext documents in this packet, click on the box below to return to the introductory page.

Introductory Page