Density is a measure of how much mass is contained in a given volume. It tells us how tightly packed the particles of a substance are. For example, if you have two objects of the same size, the one that feels heavier has a higher density. This concept helps us understand why some objects, like iron, sink in water, while others, like wood, float. To calculate density, you can use the formula: density = mass/volume. This means you divide the mass of an object (measured in grams) by its volume (measured in cubic centimeters or liters). Understanding density is important in fields like science, engineering, and even cooking.