Please take a few minutes to read the following information before beginning the tutorial. The links found within this tutorial: Within this tutorial are various links that have been colour-coded according to priority and source. The following is the legend for each link colour. Optional Internal Link: The information provided within this link is not necessary to the tutorial but is provided for greater knowledge and understanding of the topic discussed. This link is based on the same server as the tutorial, and has navigational devices that will enable the user to return to the section where they left off. Optional External Link: The information provided within this link is not necessary to the tutorial chapter. This link is not based on the same server as the tutorial. The user need only click on the toolbar "BACK" button to return to the tutorial. If the user wishes to explore the external link, bookmark your place in the tutorial and/or note the URL before going to the external link. Navigating this tutorial: A navigational banner is located at the top of each page. To select a chapter, place your mouse arrow over the word. This is a useful tool for reviewing chapters. To maximise comprehension of the material, it is recommended that the user follow the navigational links as they are set out by the author. To do this, click on the "Introduction" and follow the directions. Click on the left arrow to return to the main section from a bluedot link, or click on the right arrow to proceed through the tutorial. Ideal display of this tutorial: This tutorial is optimized for 800 x 600 display. It is best viewed with Netscape 3.0 or higher. It is recommended that the user download at least Netscape 3.0, Microsoft Internet Explorer, or another comparable browser. The Britannica search box in this tutorial: Britannica.com has selected this site as one of the best on the Internet when reviewed for quality, accuracy of content, presentation and usability. A Britannica search box is available on the bottom of each page of this tutorial. With it you will gain direct access to Britannica's award-winning content, including the Encyclopaedia Britannica. Your query will open another browser window so you will never have to leave this site to access Britannica content.