What Is the Largest Galaxy in the Universe?

You might think this question would be easy to answer. If it's big, it should be pretty straightforward to find, right? Yeah, well, the Universe isn't always that simple. First, what's a galaxy? Basically, it's a collection of stars, gas, and dust (as well as invisible dark matter) bound together by its own gravity. Some are elliptical (giant puff balls), some have disks and spiral arms, some are irregular (shapeless), and some peculiar (they have a shape, but it's ... weird). If you need a refr...