Lemons are very beneficial: their acidic note provides many dishes with that ‘je ne sais quoi’, and they are also very rich in vitamin C. There are many different varieties depending on country of origin and cultivation area. Whether the colour of the skin is light, lemon yellow or has green patches has nothing to do with ripeness. The thinner the skin, however, the juicier the lemon.
Lemons do not originate from Italy or Spain, by the way - their original home was in West Asia, the Indian Subcontinent and China. Lemons were taken to Spain in the 13th century by Arabs, and lemon trees have meanwhile become native to all countries with warmer climates.