To understand that infrared light bulbs used for heating can work, you need to know a little physics. All light bulbs that look vaguely like those Edison invented give off infrared heat. They work because a little element is heated up and this in turn gives of the visible light that we enjoy when we switch on our lights. It also gives off heat - as you will know if you have ever touched a light bulb that has recently been switched off - and this heat is in the infrared range.
For most light bulb applications this heat is an unwanted but inevitable by-product. In fact it is generally a waste of energy, and this is why modern energy efficient bulbs have been developed. They are cool, and do not lose all this energy through heat.
But in other applications, the heat given off can be helpful. For a start it is one of the radiant heating systems - just like the sun which also gives off plenty of heat in the infrared ranges. So some bulbs have been specially designed to screw into a standard bulb socket yet give off heat in place of light.
There are plenty of designs on the market, including ones made of ceramic which claim to be less easy to break. These infrared heat bulbs are unlikely to be a sensible way of heating a house (though some people find they bring comfortable heat to the "smallest room"), but they are smart ways of heating pet cages, or for specialist applications like high gloss paint setting.