Light travels faster than anything else we know of. The Sun is about 150 million kilometres away from Earth and yet its light takes only about eight minutes to reach us! Some of the stars are so far away that their light takes many years to reach us. We do not see them as they are, but as they were hundreds, thousands or even millions of years ago!
Sometimes you can see rays of light from the Sun as they light up dust particles in the air. The rays do not bend — they seem to travel in straight lines.
Light travels in straight lines
Light from the torch travels through the holes in the first screen. But only the rays travelling through the centre hole have a straight path through all three screens. Light rays travel in straight line.