Lens flare: It's when those little blobs of color or streaks of light appear in movies— and it's completely taken over Hollywood.
Lens flare's story is a technical and aesthetic one that goes back as far as Hollywood itself. As the above video shows, lens flare has become an unavoidable phenomenon with a storied history.
Aesthetically, trends have shifted from masking flare to embracing it. Once Cool Hand Luke and other '60s movies broke the unwritten rule against flare, it quickly spread from the art house to the entire Hollywood galaxy, encompassing everything from action movies like Die Hard to sci-fi films like Planet of the Apes and onward.
Technically, it's an interesting challenge as well. Advances in lens coating have made it easier to avoid flare, but it's still a desirable look for some. One of the best ways to introduce yourself to the physics of flare? Read some of the papers by the computer scientists who've meticulously created digital lenses to simulate it.