I see this all the time on software-related websites. They launch into the technical details without even one sentence about what it is. I could give a whole bunch of examples here but I think everyone has experienced this.
Please include something like the following on the webpage and--if there's space--in the headline too:
"R (a programming language for statistics)"
I don't mean to single out the guy who did these great tutorials. I mean this for everybody. If your software product/OS/service/language is not Photoshop, Linux, Google, or Java, then write a couple of words right at the top to explain what it is please.