This video shows a sequence of spin-resolved scanning tunneling spectroscopy images of a sample area of a bilayer of Pd/Fe on top of an Ir(111) surface (50 nm x 38 nm). Each of the 17 images took about 4 minutes to measure. In this measurement single magnetic skyrmions appear and disappear due to the injection of tunneling electrons and show up in the images as black dots. Each skyrmion has a preferred position and individual switching frequency depending on the local environment. Since the area is scanned line by line from top to bottom the skyrmions with higher switching frequency may switch not only from image to image but also from line to line, leading to a stripe-like pattern. Measurement parameters: U = +550 mV, I = 2 nA, B = -2.8 T, T = 4.2 K. This video relates to a paper that appeared in the Aug. 9, 2013, issue of Science, published by AAAS. The paper, by Niklas Romming at the University of Hamburg in Hamburg, Germany, and colleagues was titled, "Writing and Deleting Single Magnetic Skyrmions."