Why do cookies need baking soda and baking powder?

Baking soda and baking powder are leavening agents that make cookies rise, but they work differently.

• Baking soda: needs an acidic ingredient (like brown sugar or chocolate) to activate. It produces flatter, crispier cookies with golden edges.
• Baking powder: activates with heat alone, creating puffier and taller cookies.

Many recipes use both to achieve the perfect texture.