Aliasing is an effect that causes different signals to become indistinguishable from each other during sampling. Aliasing is characterized by the altering of output compared to the original signal because resampling or interpolation resulted in a lower resolution in images, a slower frame rate in terms of video or a lower wave resolution in audio. Anti-aliasing filters can be used to correct this problem. In a digital image, aliasing manifests itself as a moiré pattern or a rippling effect. This spatial aliasing in the pattern of the image makes it look like it has waves or ripples radiating from a certain portion. This happens because the pixelation of the image is poor; when our eyes interpolate those pixels, they simply do not look right.

Source: Technopedia https://www.techopedia.com/definition/1943/aliasing