[mattbit]

There’s actually two ways of seeing this: the three-domain system and the two-domain system.

The three-domain system divides life in Archaea, Bacteria, and Eukarya. In this system, Archaea and Bacteria can be grouped together as prokaryotes.

In the two-domain system, the division is between Archaea and Bacteria. In this case, eukaryotes are seen as a subgroup of Archaea.

Hope to have cleared up some of the confusion.