Audiovisual communications is at the core of multimedia

systems that allow users to interact across distances. It is

common understanding that both audio and video are required

for high quality interaction. While audiovisual information provides

a user with a satisfactory impression of being present in

a remote environment, physical interaction and manipulation

is not supported. True immersion into a distant environment

and efficient distributed collaboration require the ability to

physically interact with remote objects and to literally get in

touch with other people. Touching and manipulating objects

remotely becomes possible if we augment traditional audiovisual

communications by the haptic modality. Haptic communications

is a relatively young field of research that has the potential

to substantially improve Human-Human and Human-Machine-

Interaction. In this paper we discuss the state-of-the-art in haptic

communications both from a psychophysical and technical point

of view. From a human perception point of view, we mainly focus

on the multimodal integration of audio, video and haptics and

the improved performance that can be achieved when combining

them.We also discuss how the human adapts to discrepancies and

synchronization errors between different modalities, a research

area which is typically referred to as perceptual learning. From

a technical perspective, we address perceptual coding of haptic

information and the transmission of haptic data streams over

resource-constrained and potentially lossy networks in the presence

of unpredictable and time-varying communication delays.

In this context, we also discuss the need for objective quality

metrics for haptic communication. Throughout the paper we

stress the fact that haptic communications is not meant as

a replacement of traditional audiovisual communications but

rather as an additional dimension for telepresence that will allow

us to advance in our quest for truly immersive communication.