For extreme language nerds:

In Latin, words that originally started with “w” changed to “b” and then “v.” But some words kept the “w” sound because of custom.

Those were usually place names, words that were used a lot. The problem was that the letter V eventually became recognized as standing for the “v” sound. So newer Latin needed a way to indicate the old “w” sound. The solution was a double U. Other languages modeling themselves on the Roman system, like German,

adopted double U as well. So, it started out as two “oo’s,” and that’s why it’s called “double U.”

Old English already had its own letter for “w,” called wynn. It’s something we never see today. It was needed because Old English had words like water and we, so there was no question as to whether “w” was a real sound. The problem with wynn was that it looked too much like P and made things confusing. After the Norman invasion, as English took on French words, the wynn fell away and the French-style double U was used to indicate the “w” sound.

In French, to indicate the double U, they used “ou,” as in oui, “yes,” and ouest, “west.” After a while, they adopted the W, especially for words borrowed from other languages. By then, however, there was a print tradition of writing the two Us as V-shaped. English speakers continued to call it the “double U,” but by the time the French adopted it, late in the game, it looked like two Vs, and that’s why the French call it double vé, “double V.”