In OpenCV, image resizing is the process of changing the size of an image. This is done by either increasing or decreasing the number of pixels in the image. The cv2.resize() function is used to perform image resizing.

The function takes in three required parameters: the image to be resized, the desired size of the output image (specified as a tuple of width and height), and an optional interpolation method. The interpolation method is used to determine how the pixel values of the new image will be computed based on the pixel values of the original image.