Complex sentence: The house-visiting wassail is the practice of people going door-to-door, singing and offering a drink from the wassail bowl in exchange for gifts; this practice still exists, but has largely been displaced by caroling.
Split into simpler sentences: The house-visiting wassail is the practice of people going door-to-door, singing and offering a drink from the wassail bowl in exchange for gifts. This practice still exists, but has largely been displaced by caroling.