How many periods are on the modern periodic table?

In the periodic table of the elements there are 7 periods and 18 groups. The rows are called periods and columns are called groups. You may be getting confused by the lanthanides and actinides. These groups of elements are found in two rows at the bottom and seem to not be a part of the table. However, if you find and extended version of the table you will see that, technically, these two rows belong in Periods 6 and 7.