List of social letters.

1. Letter of congratulations
2. Letter of sympathy
3. Letter of apology
4. Letter of thanks
5. Letter of invitation
6. Letter of recommendation
7. Letter of introduction
8. Letter of appreciation
9. Letter of resignation
10. Letter of condolence

Personal Letters

- Letter of introduction
- Letter of congratulations
- Letter of appreciation
- Letter of condolence
- Letter of sympathy
- Letter of friendship
- Letter of explanation
- Letter of inquiry
- Letter of recommendation

Business Letters

- Letter of cover
- Letter of resignation
- Letter of termination
- Letter of complaint
- Letter of apology
- Letter of sales
- Letter of order
- Letter of acknowledgment
- Letter of credit

Formal Letters

- Letter of invitation
- Letter of acceptance
- Letter of regret
- Letter of RSVP
- Letter of inquiry
- Letter of complaint
- Letter of petition
- Letter of apology
- Letter of appreciation

Social Letters

- Note of thanks
- Note of invitation
- Note of congratulations
- Note of sympathy
- Note of encouragement
- Note of apology
- Note of introduction
- Note of recommendation
- Note of friendship