The Main Types of Bad Data in Event StreamsType 1: Corrupted DataType 2: Event Has No SchemaType 3: Event Has an Invalid SchemaType 4: Incompatible Schema EvolutionType 5: Logically Invalid Value in a FieldType 6: Logically Valid Value but Semantically IncorrectType 7: Missing EventsType 8: Events That Should Not Have Been ProducedPreventing Bad Data with Schemas, Validation, and TestsPreventing Bad Data Types 1–5 with Schemas and Schema EvolutionData Quality Rules: Handling Type 6: (Logically Valid But Semantically Incorrect)Testing: Handling Types 7 (Missing Data) and 8 (Data That Should Not Have Been Produced)The Role of Event Design in Fixing Bad DataFix It Once and Fix It Right with State EventsBuild Forward: Undo Bad Deltas with New DeltasThe Last Resort: Rewind, Rebuild, and RetryRewind, Rebuild, and Retry from an External SourceRewind, Rebuild, and Retry with the Topic as the SourceSummary