Reference Desk favorites

I mainly read and contribute to the Reference Desk. Here are some favorites I've selected:

Interesting questions

Tuning before the study of frequency -- How could you specify an absolute pitch before the concept of frequencies in hertz was available?

How has this image been generated? -- How is an image illustrating CGA composite artifacts generated in modern software? It involves constructing then decoding an NTSC signal, but I don't understand all of the the math involved.

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