What should you do before merging into another lane on a highway?

Before merging into another lane on a highway, it is essential to signal and check your mirrors to ensure a safe maneuver. Signaling communicates your intention to other drivers, making them aware of your plans to change lanes. Checking your mirrors is crucial as it allows you to assess the speed and distance of vehicles in the lane you wish to enter as well as your blind spots, ensuring that there is sufficient space for your vehicle before you make the change.

This two-step process helps prevent accidents by ensuring that you're aware of your surroundings and can execute the lane change safely. Instantaneously changing lanes without signaling could surprise other drivers and increase the risk of a collision. Similarly, accelerating and turning without proper awareness or planning can be dangerous, while switching off your headlights is not relevant or helpful in the context of merging, as it could hinder visibility and communication with other drivers.