Happy 100th birthday to the American-style crossword puzzle!
The first appearance in print of a "word-cross" was about December 21, 1913. There is a picture of it in the linked article. While the numbering system is a bit confusing, it gets the job done.
The publisher of the first compilation of crosswords was so embarrassed by the low-brow nature of the puzzle they refused to put their name on the book. To their surprise (and their pleasure, I'm sure) the book was an instant hit. The craze for puzzles even drove up the sale of dictionaries.
While my love of the slightly warped, British-style crosswords is well documented, I do fool around with the American version as well. A generic crossword app resides on both phone and Kindle, while the Kindle also holds both easy and medium New York Times puzzles. There's a book of easy, brain-clearing puzzles next to the recliner at home as well.
With on-line dictionaries and the ability to look words up directly in many reading applications, our useful vocabularies should be increasing. Puzzles are another way to broaden the pool of words at our disposal.
Amazon has a broad selection of crossword books. Their app store for Kindle has a plethora of electronic versions, including the Crossword by Teazel and NYT versions I have on my devices.
When you have a minute, give a puzzle a try. You just may learn something.