If you know what delay is, jitter is simply the difference in packet delay. In other words, jitter is measuring time difference in packet inter-arrival time. It is a specific phenomenon that normally exists in bigger packet switched networks. As a time shift phenomenon it usually does not cause any communication problems. Actually, TCP/IP is responsible for dealing with the jitter impact on communication.
Jitter is thus a deviation of time between the digital and analog samples (deviation of sampling rate). Jitter time distortions of playing back digital signal At upper left part of the picture, we can see the original musical signal (green) captured into digital form.
Jitter is a sample clock issue (clock deviation). Jitter appear in a moment when the electrical digital signal in line (wires) is transformed to a binary sequence. How the jitter appears [bit value (0/1) detection] To transmit music data through a line (cable), a digital bit sequence is converted to electrical form.
Video and image jitter. Video or image jitter occurs when the horizontal lines of video image frames are randomly displaced due to the corruption of synchronization signals or electromagnetic interference during video transmission. Model based dejittering study has been carried out under the framework of digital image/video restoration.