Everything does not happen FOR a cause, but it happens BECAUSE OF a cause.
And that's whats in dependent origination. Indeed! It describes cause and effect.
What dependent origination basically teaches, is that the cause of birth (and thus death and suffering) is clinging. Basically, because of delusion (not fully understanding suffering), we want to be reborn, we have a volition to be reborn, to keep consciousness going. So, it is a description of how rebirth occurs. It's an expanded version of the second noble truth, really.
So if you want the short version, here is the second noble truth:
"And this, monks is the noble truth of the origination of dukkha: the craving that makes for further becoming — accompanied by passion & delight, relishing now here & now there — i.e., craving for sensual pleasure, craving for becoming, craving for non-becoming."
So dependent origination also discusses how this suffering comes to be, and that the root cause of clinging is actually delusion, not seeing reality as it is, not seeing the first noble truth.
There are some other modern day interpretations that may have their value as well from time to time, but the above is what I think it originally describes.