Why, in some forms of poetry, do they use space in every other line.?

-I see in some poetry that every other line of writing was a space before it. An example is Poe's Conqueror Worm

"Lo! 'tis a gala night

Within the lonesome latter years!

An angel throng, bewinged, bedight

In veils, and drowned in tears,

Sit in a theatre, to see

A play of hopes and fears,

While the orchestra breathes fitfully

The music of the spheres."



Are these used to create pauses, make it look nicer, ect?Its to build up the readers' interests.
Its just a style of writing.
Very good..