Why should cooking oils be stored in tightly covered containers?

Cooking oils should be stored in tightly covered containers to prevent exposure to air, light, and moisture, which can lead to oxidation and rancidity. Proper sealing helps maintain the oil's freshness, flavor, and nutritional quality over time. Additionally, it protects the oil from absorbing unwanted odors and flavors from the environment. Overall, keeping oils well-sealed extends their shelf life and ensures better cooking results.