Ginger is grown for its spicy and zesty root. It is used in a lot of Indian and Asian cooking. Its origins are from southeastern Asia where it is a native plant. The edible root is not actually a root but a rhizome (an undergrown stem). Ginger is a tropical plant so needs stained heat and humidity to grow well. It can be grown indoors, greenhouse or polytunnels in cooler climates though.
Growing ginger from seed can be an involved process involving soaking the seed and cooling it in the fridge before keeping them about 22 degrees C to germinate. The easiest way to grow ginger is to start from an existing ginger rhizome (root). Soak this in warm water and then split into sections once growing buds form (One or two buds for each section). Plant these in the growing site.
Ginger grows in clumps from the new rhizomes so after approx 4 months of growing, you can start to harvest sections as you need. In colder climates where high temperatures are not sustainable, it is often best to wait until leaves start to die back before harvesting. When harvesting the whole plant, use some for eating and keep some for next year.