In telecommunication, the term skew has the following meanings:

1. In parallel transmission, the difference in arrival time of bits transmitted at the same time.

2. For data recorded on multichannel magnetic tape, the difference between reading times of bits recorded in a single transverse line.

Note: Skew is usually interpreted to mean the difference in reading times between bits recorded on the tracks at the extremities, i.e., edges, of the tape.

3. In facsimile systems, the angular deviation of the received frame from rectangularity caused by asynchronism between the scanner and the recorder.

Note: Skew is expressed numerically as the tangent of the deviation angle.

4. In facsimile, the angle between the scanning line , or recording line, and the perpendicular to the paper path.

Example of +1 degree (counter-clockwise) skew in a facsimile image. The red line is perfectly horizontal.

Source: from Federal Standard 1037C and from MIL-STD-188

For the meaning of skew in statistics, see Skewness.