A loose sentence, also called a cumulative sentence, is a sentence where the main idea, called the independent clause, is explained by adding more parts that describe it.
Effect
Loose sentences can make writing feel informal, relaxed, and like a conversation. However, as stated in Strunk and White's The Elements of Style (2000), using many loose sentences, especially those with two parts, should be avoided because they can create repetitive and monotonous patterns.
Alternatives
Stunk and White, in The Elements of Style, suggest that writers should change enough sentences to avoid repetition. They recommend replacing some sentences with simple ones, with sentences that have two parts joined by a semicolon, with periodic sentences that have two parts, or with sentences—whether loose or periodic—that have three parts. The choice depends on how the writer wants to show the true connections between ideas.
For example, if the writer wanted to rewrite the above examples, he could write: