What items do not use electricity or radio waves to communicate?

- Carrier pigeons: These birds have been used for centuries to carry messages over long distances. They are not affected by electricity or radio waves, which makes them useful in areas where these technologies are not available or in situations where security is a concern.

- Smoke signals: Smoke signals have been used by Native Americans and other cultures for centuries to communicate over long distances. They do not require electricity or radio waves and can be used in remote areas or in situations where silence is required.

- Signal flags: Signal flags are used on ships and in the military to communicate visually. They do not require electricity or radio waves and can be used in situations where these technologies are not available or in conditions where radio waves might be unreliable, such as in heavy rain or fog.