The **direction indicator light** is primarily intended to **signal that a vehicle is going to change direction** to the right or left. It is important to turn it on whenever you are going to turn, change direction, or change lanes, and to turn it off once the movement is completed. This light is yellow and flashes intermittently. It is mandatory for all motor vehicles, trailers, and semi-trailers.

On the other hand, the **emergency signal** is used to warn that the vehicle has a problem and may pose a danger to other drivers. To activate this signal, all the vehicle's direction lights are turned on simultaneously. This function is different from that of the direction indicator light, which is specifically used for direction changes.

Therefore, the correct answer is that the direction indicator light is used to **indicate that you want to change direction to the right or left**.