When the incense stick is lit, it releases smoke which contains the fragrance. Smoke is a form of gas that quickly spreads in the entire room along with the fragrance and thus making the entire room fragrant.
Indian incense can be categorized as Masala incenses and Charcoal incense. Masala incense is made by blending several solid scented ingredients into a paste and then rolling that paste onto a bamboo core stick. Most masala incenses are brown in color. Charcoal incense is made by dipping an unscented non-perfume stick into a mixture of perfumes and/or essential oils. Most charcoal incenses are black in color.