Junk food refers to snacks and meals that taste good but contain lots of sugar, salt, or unhealthy fats while offering little actual nutrition. Candy bars, potato chips, soda, and many fast-food items are classic examples of junk food: they fill you up temporarily but don't give your body the vitamins, protein, and other nutrients it needs to grow strong and stay healthy.

The term “junk” suggests these foods are like junk in a garage: not completely worthless, but not what you really need either. A bag of chips might taste delicious and give you quick energy, but an hour later you'll feel hungry again because your body didn't get real fuel. Compare that to an apple with peanut butter, which provides lasting energy and actual nutrients your body can use.

Junk food became popular in the mid-1900s when food companies figured out how to make cheap, tasty snacks that could sit on shelves for months. These foods are often engineered to be irresistible, combining salt, sugar, and fat in ways that make you want to keep eating.

People eat junk food, and that's normal. The challenge comes when junk food replaces regular meals too often.