Okay, here's one:
The origin of ska.

Back in the late 1950s, ska music was being developed in Jamaica. Taking inspiration from African American R&B, along with traditional music from the island, a bassist named Cluet Johnson came up with the name "Love Skavoovie" as a greeting for his friends. This progressed into the word "ska."
It should be interesting to note that reggae is actually a derivative of ska, and not the other way around.

But then, what about those new ska bands? Well, ska music comes in waves, much like the waves of the Atlantic Ocean. First Wave is the original Jamaican (some purists say this is the only music that is truly ska), Second Wave comes from England, and the Jamaican migration in the 60s and 70s, and Third Wave is in the United States, and started in the 80s. Bands such as the Toasters were among the first true Third Wave bands.
Where do bands such as the Mighty Mighty Bosstones, Less Than Jake and Five Iron Frenzy fit in? They take a lot of inspiration from Third Wave, but they are a style of music all their own (a good style, in my opinion).