Presence is a marker of another user (or users) to you. These are intelligent technology applied in social situations in order to promote a great sense of person-to-person interaction

Examples:

The double checkmarks on the Whatsapp chat application are meant to indicate a message successfully sent and a message successful received. Recently, Whatsapp has shown that  message has been read by turning the checkmarks blue (Nov 24)

• “Read” or “typing” stamps to show that a user has read your message or is typing a response.
• Online indicators to show that the user is online and hypothetically available for response. These can vary from online, offline, busy, and personal messages.

Metaphor: 

Presence indicators are a metaphor for physical interaction and try to give users a sense of immediacy and real-time interaction like they might get in the physical world. It attempts to remove the barrier of distance.

Social:

Presence is currently most often used to facilitate social interactions and messaging. Facebook uses the “read” sign and even customer support chat options show when the representative is typing. It removes some of the ambiguity of between sender-receiver that technology allowed for before (Did she get my message?) and make us confront (react to) the people we’re talking to online to more like we would have done during face-to-face interactions.

Alternatively, people use custom presence indicators outside of their intentions (to be more specific about their absence: “At a meeting“) and might post something entertaining (like an article or link) and or a short statement that doesn’t relate to their current activities.

Performative:

The effect of seeing these presence indicators can comfort and antagonize users. For instance, if something hasn’t been read and/or the user isn’t ‘online’ the user is implicitly told to wait and be patient. However, if the message is marked as read and/or the user is online, this could cause anxiety if a response doesn’t come quickly. Did the user really see the message? Did the ignore it? 

The mere…presence of the presence indicators compel people to read into them and change their behavior some how.