What action must you take when changing lanes?

When changing lanes, it is essential to check your blind spots to ensure that there are no other vehicles or obstacles present that you might not see through your mirrors. Blind spots are areas around your vehicle that aren't visible in the mirrors, making it crucial to turn your head and visually confirm that the lane you intend to enter is clear. This practice helps prevent accidents by ensuring you are fully aware of your surroundings before making a lane change.

Additional considerations, such as signaling your intent and using your mirrors, are important steps as well, but they don't replace the need to check blind spots. Always signaling after changing lanes may help inform other drivers, but if you haven’t confirmed that the lane is clear first, signaling alone isn't sufficient for safe lane changes. Checking only mirrors lacks the thoroughness required for safe driving, as mirrors do not provide complete coverage of the area around your vehicle. Changing lanes without signaling is unsafe regardless of whether other vehicles are present, as it can create confusion and increase the risk of collisions.