Explain bulkification and why a single-record trigger pattern fails at scale

• Triggers receive up to 200 records per batch—code must handle collections, not assume single record • Never SOQL or DML inside loops over trigger.new or trigger.old • Collect IDs in Sets, query once outside loop, map results for lookup • Apply same pattern to callouts, aggregations, and email sends • Test with 200+ record bulk loads in unit tests using Test.loadData or programmatic inserts • Use trigger handler framework separating recursion control from business logic • Monitor query rows and CPU time in debug logs during bulk operations