The moment we have all been waiting for is here -- finally!

President Obama and former Massachusetts governor Mitt Romney will debate one another tonight in Denver, a set-to that is being cast as a decisive moment in the race. 

We are flooding the zone with debate coverage -- live tweeting! Wonk|Fix! 10 most memorable debate moments! -- but in the long dark tea time of the soul between now and the start of the debate at 9 pm eastern, there's not much to do but speculate and wonder. Of course, that's what we do best.

We've spent the last few days gathering  -- and even making! -- some cool/helpful charts that help explain what people expect out of the debate tonight and the likely effect it will have (or won't have) on the race.  We culled that list to six. They are below. Have a chart, graph or infographic on the debates we should add? Send us a link at chris DOT cillizza AT wpost DOT com and we will add it!

1. People think President Obama is going to win the debates.

2.  Debates have, historically, done little to change immediate dynamic of the race.

3. Debates have also done little to change the final result of a race -- although they do tend to have a bit of margin-slimming impact on the frontrunner.

4. Lots and lots of people watch the debates.  In 2008, 52 million people watched the first debate between then Sen. Barack Obama and Sen. John McCain. (Almost 70 million people watched the vice presidential debate between Joe Biden and Sarah Palin.)

5. Fewer people watch the debates than once did.

6. The older you are, the more likely you are to watch the debate.