What is the windows server 2012 feature that enables you to maintain previous versions of files on a server, so that if users accidentally delete or overwrite a file, they can access a copy?

Why were most movies from the late 1890s until the early 1930s only filmed in black and white? there were only a few people who could afford the technology to produce color motion pictures back then. audiences did not want color motion pictures until later. the film used to make color motion pictures often overheated, which was a safety hazard, so it was generally not allowed. color films had to be hand-colored, frame by frame.