What is a light-year?

A light-year is a unit of distance used in astronomy, equivalent to the distance that light travels in one year.
The value of a light-year can be found by multiplying 300,000 km/s (the speed of light) by 365 days (the duration of a year) and by 86,400 (the number of seconds in a day).
The distance from the Sun to the Earth is 150,000,000 km, which is equivalent to 8 and a half light-minutes.
The closest star to Earth (excluding the Sun) is Proxima Centauri, which is located 0.2 light-years away.