Postal service
concept · 550 BC · Ancient world
A letter delivery service (the Yam relay, the Persian post).
Principles and materials it uses
- Steam locomotive — uses. Mail trains.
Where it is used
- Letter box — is used in. The post.
- Postage stamp — is used in. Paying for delivery.
History: what it evolved from and what it influenced
- Email — evolved into. Electronic mail.
What it is a kind of
- Pneumatic tube — includes. The post.