There are four basic onion varieties: white, yellow, sweet, and red. Some will make ya cry, some are a little sweeter.

• WHITE ONIONS-  are a mild with a touch of sweetness. They are best used raw or in soups. 
• YELLOW ONIONS–are what you’ll commonly see needed in a recipe. They have a nice balance of sweetness and savoriness and are best used for cooking. Of this list, the yellow onion is the one you should never not have in your home kitchen.
• SWEET ONIONS- cook in a similar way to yellow onions. Because they are sweeter than the rest, they’re best enjoyed raw, in salads, salsa, or sliced on burgers or sandwiches.
• RED ONIONS- are mostly used raw. They turn a strange, dark blue color after cooking which makes them less appealing. If they are used for cooking, it’s typically quick, such as on the grill or under the broiler. They’re more pungent than sweet, so make sure to slice them very, very thin.

TIPS:

1. When buying onions, make sure they are firm to the touch.
2. Don’t store your onions in the fridge! Keep them in a cool, dry, dark place, and never in a sealed container.
3. The only time you’ll want to keep onions in the refrigerator are when you’ve cut into them and used half for a recipe. Newer onions will have thin, flaky skins. Older onions have thicker, tough skins.
4. Most of the tricks to avoid tears while cutting onions don’t actually work. One that does? Goggles. If you’re a contact lens wearer and don’t suffer from the occasional onion cry, it’s because your eyes are technically blocked from gases. But the rest of us can just grab a pair of swimming goggles or these special goggles made just for onion cutting.