Gaussian filtering is a technique used in image processing to reduce noise and detail in images. It works by applying a mathematical function called the Gaussian function, which creates a bell-shaped curve. This curve helps to smooth out variations in pixel values, making the image appear softer and less cluttered. The process involves convolving the image with a Gaussian kernel, a small matrix that defines how much influence surrounding pixels have on each pixel's value. By adjusting the size of the kernel, users can control the level of smoothing, allowing for clearer images while preserving important features.