Common ragweed may be an important weed for you to identify, even if you don't care about keeping your yard weed-free for aesthetic reasons. Why? Because if you're an allergy sufferer, you should be aware that common ragweed is a major source of hay fever.
Now that you have an idea of what the leaf (or leaflet, to be more accurate) looks like, do you want to see the entire plant? Have a glance at my photo showing what ragweed looks like.