Nearest neighbor filtering is a simple image processing technique used to resize images. It works by replacing each pixel in the new image with the value of the nearest pixel from the original image. This method is quick and easy to implement, making it popular for applications where speed is more important than image quality. However, nearest neighbor filtering can result in a blocky or pixelated appearance, especially when enlarging images significantly. This occurs because the technique does not consider the surrounding pixels, leading to a loss of detail. Other methods, like bilinear interpolation or bicubic interpolation, can produce smoother results but are more computationally intensive.