Firewalls can block some aspects of the Internet, such a Java programs. Forms are, well, forms. Visitors can enter information, which can then be forwarded to you. Click to see examples of form elements. Frames are HTML formatting elements.
Frames are like independently-moving windows inside a larger window frame.
Click to see an example. Frames are very useful if, for instance, you have a long document, but you don't want the reader to have to scroll back to the top of the page to find the navigation buttons. GIFs can also be animated . Click to see examples. See also JPEG .