Computer Terminology - What Words Cause Confusion?

Right now I'm in the middle of preparing a workshop for the annual ABE Summer Institute.  OK, I'm preparing 3 workshops and one discussion group, but there's one session in particular that I'm crunching away on more vigorously than the others.  It's titled "Everything You Wanted to Know About Your PC, but were Afraid to Ask."  It's targeted at the teachers in our field who have found themselves bypassed by the quickly moving world of computers.

My hope is to orient participants enough (and reduce anxiety enough) that they can begin trying to teach themselves new computer skills.  I'm focusing on a few fundamental Windows tasks (like using the taskbar and right-clicking for contextualized menus), Internet and browser basics, and perhaps most importantly, clarifying vocabulary so that teachers can more fully participate in the technology conversations going on around them.  To this end, I'm coming up with a list of specialized computer terminology that has become ubiquitous, but often needs explaining to people who are not comfortable with computers.  Words like "upload" and "download" are on there.  "Browser" and "URL" and "Wi-Fi" are too.

But my question for you, dear readers, is:  What words do you think cause the most confusion?  Is it functional stuff like I've listed above?  Or is it names of products/services like Twitter and YouTube that cause anxiety among the uninitiated?  If you were a rank novice in the land of computers, what terms would you most want defined and clarified so that you could begin teaching yourself?

Send me your thoughts in a comment, or look me up on Twitter or email.  I'm not hard to find.