Last month, "Spider-Man: Across the Spider-Verse" was released in theaters to critical acclaim and success at the box office. The movie features a vibrant animation style that its predecessor popularized: a unique blend of 2-D and 3-D elements. As more blockbuster movies pick up the style, we seem to be entering a new age of animation. We talk to an animation and film history expert about how the medium has evolved over time, and how this new style emerged.