What HAARP actually is

I'm sure this has already been covered on this blog, but I am going to post this anyway. Mostly because I don't want to go through the whole blog looking for it.
I just read a very nice post about why HAARP is surrounded by conspracy theories, but I realized that I don't know what HAARP's actual purpose is. My solution to this problem? I read the Wikipedia page. Its primary purpose is to analyze the ionosphere. Using this analyses, we could create enhancements in the ionosphere that would lead to technological advancements in radio communications and surveillance. The frequencies emitted by HAARP that are so attractive to conspiracy theorists are used to test "basic natural processes that occur in the ionosphere under the natural but much stronger influence of solar interaction, and how the natural ionosphere affects radio signals." HAARP is where most of our knowledge on the ionosphere comes from. It is a very difficult region of the atmosphere to study because it is too high for balloons to reach, but satellites can not be used there because the air is to thick.
After all this though, I still was not sure what exactly HAARP is. In short, it's just a bitchin radio tower.