lights是什么意思？

And, perhaps, similar to sails, they make a useful back-up for when the lights go out.

On the other hand,there have been hundreds of thefts and cases of deliberate damaging of public property, which usually involves breaking windows or lights or writing on walls.

Just before people began entering the hall, Larry dimmed the lights and turned up the sound system, which was playing soft music, hoping to create a warm personal atmosphere for the speech.

Why did Larry dim the lights and turn up the sound system before people entered the hall