Different textbooks give different answers to this question. The confusion comes from the fact that the two lowest vertebrae -- the sacrum and the coccyx -- are each one bone, but they are made up from smaller bones fused together.
There are 24 separate vertebrae; then there is the sacrum, which is formed from 5 fused vertebrae; and finally the coccyx, which is formed from between 3-5 fused vertebrae. Therefore, if the coccyx and sacrum are each classed as one vertebra, then there are 26 vertebrae. If the fused vertebrae are all counted separately, then there are 32-34 vertebrae.