What is a “slash line”?

I’ve noticed several baseball analysts use a slash line when noting a players’ performance.  It’s not as common on TV so I just recently learned it.  An example would be in 2009 Michael Young had a slash line of .322/.374/.518.

The percentages are:  Average/On-Base Percentage/Slugging Percentage

AVG = H/AB.

Most people know that a good average is usually around .300.  Ted Williams had a good way of putting it:  “Baseball is the only field of endeavor where a man can succeed three times out of ten and be considered a good performer.”

OBP = H + BB + HBP/AB + BB + HBP + SF

This measures how often the batter reaches base.  A good OBP is .370.

SLG = (1B) + (2 x 2B) + (3 x 3B) + (4 x 4B)/AB

This measures the power of a hitter.  A good slugging percentage is .500 or higher.