Corpus Christi (Fronleichnam) is a regional statutory public holiday that always falls on a Thursday. In southern and western Germany, the key planning question is whether Friday becomes a bridge day.
Culturally, the day is characterized by festive Corpus Christi processions. The Host is carried in a valuable monstrance under a canopy through decorated streets, past altars and flags.
Public holiday in several states, not nationwide. The decisive place is not always the home address: workplace, school location and travel destination can each change the answer.
Check first whether Corpus Christi applies at the concrete location. Then Friday decides whether the regional Thursday becomes a four-day block. That check should happen before booking travel, moving meetings or assuming that school and work calendars line up.