What do they burn in church?

What is the purpose of burning incense?

Incense is used to freshen up the scent of indoor areas, for spiritual purposes, for health, and more. Like anything else that emits smoke, incense smoke will be inhaled when using it.

Why do Catholic churches burn incense?

The smoke of burning incense is interpreted by both the Western Catholic and Eastern Christian churches as a symbol of the prayer of the faithful rising to heaven.