Which maneuver is essential before changing lanes?

Before changing lanes, checking mirrors and blind spots is an essential maneuver as it ensures that the driver is fully aware of their surroundings and any other vehicles that may be in the adjacent lane. This practice is critical for maintaining safety on the road, as it helps to avoid potential collisions with vehicles that might not be immediately visible in the mirrors.

Mirrors provide a view of the traffic behind and to the sides of the vehicle, while checking blind spots gives the driver a complete picture of the road conditions. By combining these two measures, a driver can make an informed decision about whether it is safe to change lanes. This step reinforces defensive driving strategies and promotes situational awareness, which are crucial elements in any driving situation.