The edible ginger root is the rhizome of the Zingiber plant. It is native to china but is now grown in Asia, Africa, South america and the caribean. In India, China and Japan, ginger is an ingredient for cuisine, and also used as a spice or to make juice. In Africa, it is used to make juice and as a spice. You can google many recipes for the african ginger juice ( here is one of them, the Malian one ;)) and other ginger recipes.
Ginger is used as a medicine all over the world.
Ginger root is very rich in fibers and contains essential oils such as gingerol, zinger one, farnesene, and shogoal as well as essential nutrients and vitamine B-6 and B-5.
Many serious medical studies have found that ginger can help prevent colon cancer by reducing the colon inflammation. It has antioxydant, anti-inflammatory, anti-tumor effect on cells and is proven to kill ovarian cancer cells. It helps reduce the nauseas provoked by chemotherapy or during pregnancy. It helps reduce blood pressure in hypertension cases and helps restore liver damage caused by acetaminophen and so on.
You can find a great article about medical studies on ginger roots here.
I personally use ginger when I have respiratory infection, and it works most of the time. Some people will make ginger tea, but what works well for me is to chew thinly sliced ginger seasoned with sea salt several time a day. the antibacterial action of the sea salt combined with the anti-inflamatory effect of the ginger has great results.