A Substitute for the gestural communication over the Internet is the use of :

Concept — In a face-to-face exchange a large part of the meaning travels through a non-verbal channel: gestures, facial expression, posture and tone of voice. Purely text-based communication removes that channel, so a medium that carries only typed words needs a written stand-in that restores the sender's expression and attitude to the message.

Application — Emoticons are marks built out of punctuation or small pictorial symbols, such as :-) , :-( and a smiling face, that are typed inline with the message itself. Because they sit beside the words and colour one particular sentence, the reader decodes them the way a listener decodes a smile, a frown or a raised eyebrow in person. In the internet medium they therefore carry out precisely the paralinguistic work that gestures do face to face.

Cross-check — The remaining choices belong to other communicative functions:

• Infographics present data, statistics or processes as designed visual layouts; their purpose is quicker comprehension of information, not conveyance of the sender's momentary expression.

• Photographs record how a subject appeared at a moment in time; they document a scene rather than accompany a sentence as an expressive cue.

• Anonymous attachments are files forwarded without identifying their sender; this concerns provenance and file transfer, not non-verbal expression.

Result — The substitute for gestural communication over the Internet is the use of emoticons.