What are hot pixels in a DSLR camera?

Why do hot pixels occur in an image? Is hot pixel problem a hardware related or image related? How it develops in a camera if it is hardware related? Is it too serious problem to not purchase a DSLR or a DSLR with such problem like Nikon D7000? Is there any way to fix it? How to test if a certain camera is having this problem before buying? Please explain. Also please post a picture highlighting hot pixel in an image if possible.

A hot PIXEL? Is usually a damaged pixel in the camera that is always blown. It's broken hardware.
Hot spots in an image result from something reflecting a lot of light and may be referred to as hot pixels. Glitter causes hot spots, lots of metallic eye shadows cause it. Anything that reflects light into the lens that is considerably brighter than the exposure of your image.
There are cameras that have a slightly higher dynamic range than others. Is it a reason not to buy the D7000? NO! The D7000 is the greatest thing since sliced toast in the crop sensors-and I don't shoot Nikon. A LOT of the pros who are shooting full frame are using the new D7000 as a second body. It's an awesome unit.
The average professional user won't even notice the difference. The only ones who would Really see it are the extremely high end work that is also extremely specialized.