Atto means eighteenth in Danish, Attosecond means 1/1,000,000,000,000,000,000th of a second.
In one attosecond, light can travel the length of 3 hydrogen atoms.
Generally, light can travel 7.5 times around the earth in 1 second. However, in an attosecond it can barely move from one end of the molecule to the other end.
Another way to think about this is:
one attosecond : one second = one second : 32 billion years.
The Flash, a superhero from a comic book who has the ability to run faster than the speed of light, has the ability to see events that occur for less than one attosecond, which, for humans, is less time than it takes to blink an eye.
