The artist Eadweard Muybridge produced the above images. He was revered for his work because he set up a system of trip-wires that would each activate a shutter on a set of cameras. So as a person or animal ran past, he could capture it in a variety of sequenced possess. Like with the image above, entitled Horse in Motion, he captured a horse as it galloped. Besides the process used, this image was important because it was the first time anyone had noticed that all four of the horses feet leave the ground at the same time, during one point of its gallop.
In simple terms, high resolution photos are best for printing and enlarging, and web-sized photos are best for computer use (website, social media, email, digital documents).