Dry ice is the solid form of carbon dioxide (CO2). It's called "dry ice" because it does not melt like wet ice. Instead, dry ice converts into carbon dioxide gas. Because dry ice is extremely cold ( -109°F/-78.5°C), non-toxic, and completely dry, it is commonly used as an expendable refrigerant to ship frozen food or medical products or to cool materials during production. The other major use of dry ice is for dry ice blast cleaning, an effective and environmentally friendly way to clean industrial equipment.
Yes, providing you observe some simple safety rules. The CO2 gas that sublimates from the dry ice is non-toxic (it is the same gas used in all carbonated drinks), however, in a confined space it poses an asphyxiation risk. Dry ice is also extremely cold at -78.5°C which means that if it is in contact with human skin for longer than a second or two it can lead to a "frostbite" like burn. Protective gloves should always be used.