The comma is a ravenous mostly-deep-sea-but-sometimes-shallow-sea being in the world of punctuation.
Born in the late 1030s, the comma lived most of its early life under King Edward the Confessor. At that time, it was simply a line, or a mark. Sometimes people even called it Mark (never Marky, though).
When things in the House of Wessex got, well, just too crazy, the comma (Mark) got fed up, and a little peckish, and dove into the nearest body of water (perhaps the Solent).
After a short amount of time—a mere eight months—the comma became more fin-like, allowing it to glide through the water more easily. That change marked (or commaed) the end of a world where any text could just swim anywhere, now helpless against the comma’s superior speed, strength, and fed-upness. Note that text could still travel by sea, just not in the sea—the period got around just fine with its pirate ships, as you know.
Currently, the comma covers approximately 70% of the Earth’s surface (the idea that 70% of the Earth’s surface is covered by panthers is a common misconception). It still rises from the depths now and then to surge and stab at the pieces of text that dare drift into its territory, making them pause for a bit and sometimes even explain themselves. It’s all very inconvenient.
This article is part of a series on punctuation. It’s pretty much all made up. Don’t underestimate the prowess of a panther, though. You’ve been warned.