The Thais are a deeply religious people. For the Buddhist majority it underlies all activities and is the backbone of the Thai culture - a culture that has survived intact and independent for so long largely because of the principles of the Buddhist faith.
Ninety percent of the population are Theravada Buddhists. The Theravada school of Buddhism is based more purely on the teachings of Gotama Siddartha (Buddha) without the refinements added on by later monks. Buddhist believe that existence is suffering, suffering is caused by desire, so the elimination of desire leads to a state of perfect non suffering and non existence called nibbana (nirvana).