A jitter buffer (actually also called a de-jitter buffer) is a memory for the output of isochronous data streams. It compensates their jitter by buffering the incoming data according to the FIFO principle. This means that less of the incoming data has to be discarded due to late receipt (reducing the effective packet loss rate). However, this also increases the overall delay of the data. Jitterbuffers are used, for example, in voice and video applications over IP networks. For streaming applications (e.g. video over the Internet), it makes sense to work with high levels of the jitter buffer, as this improves the absence of interference during playback, while the delay usually remains unnoticed (except when switching between different channels). With IP telephony, for example, the delay is also disturbing and you have to compromise between more delay and less packet loss rate.
Source: https://de.wikipedia.org/wiki/Jitterbuffer Further Information