Signal, signals, signaling, or signalling may refer to:

Scientific concepts

• Signal (electrical engineering), a varying quantity that can carry information.
• Signal processing, the field of techniques used to extract information from signals
• Cell signaling, in biology, the system of communication that governs basic cellular activities and coordinates cell actions
• Signal (biology), an electrochemical communication activity in an organism
• Two theories in different disciplines of "honest signalling" when deception may be incentivized:
• Signalling theory in evolutionary biology, a theory stating how organisms signal their state to others with respect to evolutionary survival and reproductive fitness
• Signalling (economics), how market actors can signal their intentions and values to others in economics
• Signalling game, signalling theories in evolutionary biology and economics expressed in terms of game theory

Computing:

• Signal (computing), an event, message, or data structure transmitted between computational processes
• Signal programming, a variety of event-driven programming
• Signals and slots, a signal-driven software design pattern

Communications

• Signals used in various kinds of transport:
• Traffic light
• Railway signal
• Semaphore
• Beacon
• International maritime signal flags, using the International Code of Signals
• Signals (military), a name that refers to military communications
• Distress signal
• Smoke signal (See also Early telecommunications)
• Signalling (telecommunications), a part of some communication protocols

Names

• Signal (band), a Bulgarian rock band
• Signals (album), an album by progressive rock band Rush
• Signal (magazine)
• Signal (toothpaste)
• Signal 1 and Signal 2 radio stations
• Signaal (now Thales Nederland), a Netherlands based defence company
• Signal Systems, a company of the McLean Group of Companies

Other

• Any implicit, subtle, or disguised message, in situations such as:
• Partnership card games (see Signal (bridge))
• Signals in legal citations
• Kent (game) a card game also known as Signal or Kemp

See also

• The Signal