According to HowStuffWorks, the most common unit for describing stellar distance is the light year. Contrary to what the name may imply, the light year is a measurement of distance and not time. It is the distance that light can travel in the span of one Earth year.
According to HowStuffWorks, light travels at 186,000 miles per second. Therefore, a light second is 186,000 miles. A light year is the distance that light can travel in an entire year, or 186,000 miles per second multiplied by 60 seconds per minute multiplied by 60 minutes per hour multiplied by 24 hours per day multiplied by 365 days per year equals 5,865,696,000,000 miles per year. According to NASA, the closest star to the sun is Proxima Centauri, at approximately 4.22 light years away.