Bilateral organisms exhibit bilateral symmetry, meaning they can be divided into two mirror-image halves along a single plane. This type of symmetry is commonly observed in many animals, including humans, where the left and right sides are roughly equal in size and shape. Bilateral symmetry is often associated with cephalization, the concentration of sensory organs and nerve cells in the head region, aiding in movement and environmental interaction. It plays a critical role in the development and evolution of various organisms throughout the animal kingdom.