Characteristics
The periodic sentence emphasizes its main idea by placing it at the end, following all the subordinate clauses and other modifiers that support the principal idea. The sentence unfolds gradually, so that the thought contained in the subject/verb group only emerges at the sentence's conclusion. Obviously artificial, it is used mostly in what in oratory is called the grand style.
It is the opposite of the loose sentence, also continuous or running style, where the subject and verb are introduced at the beginning of the sentence. Periodic sentences often rely on hypotaxis, whereas running sentences are typified by parataxis.
Cicero is generally considered to be the master of the periodic sentence.
Read more about this topic: Periodic Sentence