The onion is a food that was gathered and eaten by prehistoric humans in Asia. It has been continuously used throughout the history of mankind. Through the ages medicinal qualities have also been attributed to the bulb.
Onions are of two general types.
The strong flavored globe onions have a globular shape and may be of the white, yellow, or red variety. Milder onions are the Bermuda and Valencia varieties. The Bermuda have a flat shape and a sweet flavor while the Valencia tend to be larger, elongated, and white, yellow or light brown. Green onions, which are immature bulbs, are sold in bunches as spring onions or scallions and are crisp and tender. A wet or damp neck indicates decay, as do discoloration and mold.