What's the substance used in churches characterized by releasing smoke?

The word "incense" is derived from the Latin incendere, which means "to burn". The use of incense in religious worship predates Christianity by thousands of years. First in the East (circa 2000 BC in China with the burning of cassia and sandalwood, etc.), and later in the West, incense use has long been an integral part of many religious celebrations. Incense is noted in the Talmud, and the Bible mentions incense 170 times. The use of incense in Jewish temple worship continued well after the establishment of Christianity and certainly influenced the Catholic Church's use of incense in liturgical celebrations.