Black and Yellow Garden Spider
I've never seen this before in my garden and am hoping it's a beneficial spider. Scared the crap out of me at first as I was putting stuff in the compost pile when she (I'm assuming the size means it's a female) darted up the web.
Prince George's County Maryland
Your spider is, indeed, a beneficial spider. Its Latin name is Argiope aurantia. It is in the category of spiders known as orb weavers. The female will make a new web each morning and eat the web that evening. She is a very adept predator of other insects that stumble into her web.
These spiders are not aggressive toward humans and would only bite if you tried to pick her up. While some people are more sensitive to insect/spider bites than others, generally speaking, her bite would not be serious..