What does auto.offset.reset=earliest vs latest do?

auto.offset.reset determines where a NEW consumer group starts reading when there's no committed offset. earliest: start from offset 0 (read all available messages from the beginning). latest: start from the current end of the partition (only read new messages produced after the consumer starts). For development and initial loads, earliest is common. In production, for most streaming apps, latest prevents processing stale historical data.

Expected key concepts: auto.offset.reset, earliest, latest, new consumer group, committed offset, beginning, end, historical