Signalling is theory from evolutionary biology. Signalling covers a range of behaviours and traits that that convey a message about the sender, whether in terms of their status, their mate-appeal, their potential as a useful ally, or their threat as potential foe. A signal can be a gratuitous physical attribute such as the peacock's tail, or a conspicuous behaviour such as stotting or pronging by springboks and gazelles . The handicap principle (Amotz Zahavi) suggests signals need to be costly to the sender to be credible. Signalling can work within and across species.
In human terms, the range of signalling can be very broad and has broken through to popular culture in the form of "virtue signalling" i.e. disingenuously sending a message about one's moral value through a political statement or position. The term "signalling" has analogous meaning in contract economics.