Ellen Brown, author of The Complete Idiot’s Guide to Slow Cooker Cooking (Alpha, $17, www.amazon.com), tackles common questions about one of the most underrated kitchen appliances.

Why use a slow cooker? A slow cooker produces an even, low, moist heat that eliminates the need for stirring, so you can simply prepare a meal, then leave it to cook. And unlike an oven, says Brown, a slow cooker is very energy-efficient. Plus, you can leave it on all day, even when you’re out of the house.

Is it safe? Food is susceptible to bacteria growth between 40° and 140° F. “A slow cooker brings food through the danger zone so fast, bacteria cannot take hold,” says Brown. But keep this in mind: If you brown your meat in advance, don’t store it in the refrigerator mixed with raw or partially cooked ingredients or you’ll increase the risk of contamination.

Will the cooker boil over? Fill it at least halfway (for even cooking) but no more than three-quarters full and you’ll be fine. Your real concern should be about losing heat — and slowing down the cooking — each time you lift the lid. Always keep the pot covered, says Brown. (Buy one with a clear lid so you can peek through.) If you must lift the lid, tack on 5 more minutes of cooking time.

Can I use a cooker with a conventional recipe? “Go ahead and make your aunt’s famous barley stew,” says Brown. “But cut back on the amount of liquid by a quarter, since you have a much slower rate of evaporation than in a regular pot.” Follow cooking times used for similar slow-cooker dishes.