This is an entry in our Disneyland 101 Glossary: Disneyland Resort definitions in under 101 words, from Mouse Brief.
Nighttime Spectaculars are shows that take place after dark at Disneyland Park and Disney California Adventure Park. These shows typically take advantage of their dark setting by featuring fireworks, projections, pyrotechnics and other light effects. These effects are set to music and usually a narrative. Popular examples of these shows include World of Color at Disney California Adventure Park, and at Disneyland Park there is Fantasmic! and the many varieties of firework shows (Fantasy in the Sky, Disneyland Forever, Wondrous Journeys). Particular holiday seasons or festivals usually feature special versions of these nighttime spectaculars.