Brown Sugar
Brown sugar is granulated sugar with molasses, giving it moisture, color, and a caramel-like flavor. It is useful in baked goods, sauces, toppings, and glazes.
Identity
Moist sweetener
Molasses adds softness, color, and caramel notes.
Pack brown sugar only when a recipe asks for it, because packing changes the measured amount. If it hardens, it can often be softened before use rather than discarded.
Reference image
Brown Sugar reference image.

Source: Wikimedia Commons
Used In Recipes
Substitutions
Coconut Sugar -> Brown Sugar
⅓ cup lightly packed coconut sugar or brown sugar
The source lists this as an alternative in the same ingredient row.
Source: Strawberry Rhubarb Crisp
Coconut Sugar -> Brown Sugar
⅔ cup lightly packed coconut sugar or 1/2 cup packed brown sugar
The source lists this as an alternative in the same ingredient row.
Source: Vegan Chocolate Chip Cookies
Light Brown Sugar -> Brown Sugar
2/3 cup (142g) light brown sugar or dark brown sugar, packed
The source lists this as an alternative in the same ingredient row.