Home > Encyclopedia of Science > Telegraph

• History
• Words to Know
• The modern telegraph
• Operation of the telegraph
• Historical importance

A telegraph is any system that transmits encoded information by signal across a distance. Although the word telegraph is usually associated with sending messages by means of an electric current, it was used originally to describe a visual system for sending coded messages.

Until the telephone became a workable system, the telegraph was the standard means of communication between and within metropolitan areas in both Europe and the United States. Telephones did not make the telegraph obsolete but rather complemented its use for many decades.

Today, telegrams and telexes still use telegraphy (the sending of messages by telegraph) but are...