Citron
A source of confusion is that "citron" or similar words in French (and other languages), and English are false friends, as they refer to the lemon. Indeed, into the 16th century, the English name "citron" included the lemon and perhaps the lime as well.
Citron
Today the citron is used for the fragrance or zest of its flavedo, but the most important part is still the inner rind (known as pith or "albedo"), which is a fairly important article in international trade and is widely employed in the food industry as succade, as it is known when it is candied in sugar.