message
Airmail – Service which transports mail by air
Amateur radio emergency communications – Fallback service
Beacon – Device used to attract attention
Communications satellite – Artificial satellite that relays radio signals
Communication studies – Academic discipline
Drums in communication – Drums used for long-distance signalling and communications
Email – Mail sent using electronic means
Emergency Alert System – Method of emergency broadcasting in the United States
Encryption – Process of converting plaintext to ciphertext
Express mail – Accelerated mail delivery service
Flag semaphore – System to transmit information by hand
Instant messaging – Form of communication over the Internet
List of interstellar radio messages
Mail – System for transporting documents and other small packages
Message in a bottle – Form of communication
Network packet – Formatted unit of data carried by a packet-switched network
Optical telegraph – Communication along a chain of towers using mechanically operated paddles or shutters
Pioneer plaque – Plaques on the Pioneer 10 and 11 space probes with pictorial messages about humanity
Pony Express – 1860–1861 mail service in the United States
Radio – Technology of using radio waves to carry information
Semaphore – Mechanical apparatus used to send messages
Semiotics – Study of signs and sign processes
Sign language – Language that uses manual communication and body language to convey meaning
Smoke signal – Smoke used as a mode of communication
SMS – Text messaging service component
Telegraphy – Long distance transmission of text
Telephony – Field of telecommunication services
Television – Telecommunication medium for transmitting and receiving moving images
Voicemail – Voice message storage and retrieval
