.swf files are Flash format animations

They can be interactive. The ITPs are Flash animations. To view Flash files you need to install the free Flash player from Adobe and click on the Adobe Flash Player button.

.exe files are executable programs that run on Windows PCs

After downloading an .exe file, double-click on it to run it. The .exe files on the web site are stand-alone versions of the ITPs that will run on PCs without the Adobe Flash Player installed.

.hqx files are compressed files for the Apple Mac

They can be uncompressed by Mac OSX by double-clicking the downloaded files. The .hqx files on the web site contain stand-alone versions of the ITPs that will run on Macs without the Adobe Flash Player installed.