Nobody seems to agree where exactly lemons originally came from, but it was probably India, China or Southeast Asia. By the first century they were already being cultivated in Palestine and by the second they were already being exported to Rome.
During the 8th and 9th centuries the Moors planted lemons all over Northern Africa, Southern Spain and Italy. Columbus and the first Spanish and Portuguese explorers introduced lemons to the "New World".
Lemons are an indispensable and irreplaceable flavoring in kitchens all over the world. They balance out the sweet and the savory. Just a little squeeze will bring out the flavor and improve just about any dish you can think off. Fresh lemon juice will freshen fish or poultry and tenderize meat.
The zest and juice are used in innumerable sweet preparations, from lemonades and sherbets, to cakes, pies, frostings or to flavor and prevent sugaring in jams and jellies.