Order of Execution

Knowing the save order lets you answer "why didn't my validation rule see the value my trigger set?" style questions.

The sequence (simplified)

1. Load the original record (update) or initialize new values (insert).
2. System validation — required fields, field formats, max length (and layout rules from the UI).
3. Before-save record-triggered flows (fast field updates).
4. Before triggers (before insert / before update / before delete).
5. System validation again + custom validation rules.
6. Duplicate rules.
7. Record saved to the database (not committed yet).
8. After triggers.
9. Assignment rules → auto-response rules.
10. Workflow rules — field updates here re-run before/after update triggers once more.
11. Escalation rules.
12. After-save record-triggered flows (and other flow automation).
13. Entitlement rules.
14. Roll-up summary recalculation on the parent (the parent goes through its own save).
15. Criteria-based sharing evaluation.
16. Commit to the database.
17. Post-commit: emails sent, async Apex (@future, queueable) and outbound messages start.

Consequences you should be able to explain

• A before-save flow runs before your before trigger — your trigger sees the flow's changes.
• Validation rules run after before triggers — so values set in a before trigger are validated.
• An after trigger that updates the same object starts a new save cycle for those records (recursion risk).
• A workflow field update can make your update triggers fire twice in one transaction.
• Async work and emails only happen after commit — if the transaction rolls back, they never run.

Example

trigger LeadTrigger on Lead (before insert) {
    for (Lead l : Trigger.new) {
        if (String.isBlank(l.LeadSource)) l.LeadSource = 'Web';
    }
}

A validation rule ISBLANK(LeadSource) will not fire for these leads, because validation rules run after the before trigger filled the field.

Interview questions

1. Do validation rules run before or after before-triggers? → After.
2. Why might an update trigger run twice? → Workflow field update re-fires it (or recursion from an after trigger).
3. When are emails from a trigger actually sent? → After commit.