The only reason I can see for using this tag is to create the indented paragraph, otherwise you could use good old quotation marks to indicate a quote. Good for centering major headings, a paragraph that you want to stand out, a table or image you want to appear as centered, and any other visual element you want in the center of the page. Lists by bullet , number and indentation come in a wide variety. Images are placed with specific tags that require detailed explanation. Old browsers do not show tables, which are important in page design, so people should update their browsers to be able to view them.
Forms are what the name implies, a typical form that the reader fills in and submits.
I saw one once somewhere that even took your submission and added it to a line graph that showed you where your answer stood in relation to everyone else who had submitted information before you. Such magic is way beyond my skill level. Some of these examples won't work on your browser. They don't work on mine either. Wait for HTML3 to arrive.