Horizontal Rows of the Periodic Table Are Called?

The horizontal rows on the periodic table are referred to as Periods. The vertical rows are referred to as Groups.
Q&A Related to "Horizontal Rows of the Periodic Table Are Called..."
 Columns (the lines like this : l. are called. groups. and. Rows (the lines like this : are called. periods. http://wiki.answers.com/Q/What_are_horizontal_rows...
 A period is a horizontal row in the periodic table of http://www.chacha.com/question/what-is-a-horizonta...