Shard by Business Domain: Each service can own its own database, and the data?

Short answer: can be partitioned by business domain. For example, the Order Service might have its own database, and the Customer Service has another one.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.