PowerPoint is software for creating and displaying presentations, typically used in conjunction with a video projector. It is the standard these days at scientific conferences (you might also see OpenOffice or PowerBook display tools). Examples of both PowerPoint and OpenOffice presentations are available on the course web page.
One disadvantage of these tools is that it can often be hard to typeset equations (not that you should have too many equations in a presentation anyway...). An easy workaround is to generate the equations in LATEX first, convert the output to a rendered image, then import it into the presentation.