A loose or cumulative sentence is a type of sentence structure that is used when there is a need to show degrees of significance in the constituent ideas. Loose structure and periodic structure are two variations that can be differentiated on the basis of the position of the main clause and the subordinate clause. Simply put, a loose sentence starts with a main clause, followed by a subordinate clause. According to The New Oxford Guide to Writing, the loose sentence approaches the cumulative style, when the number of subordinate constructions increase. So, a cumulative sentence is defined as a sentence in which the main clause comes first, followed by subordinate modifiers or trailing elements. These are often used in cases when one wants to put forth the main idea first, and provide details in order to explain the idea further. These details could be in the form of one or more subordinate or dependent clauses or phrases. A periodic sentence is another type of sentence structure where the writer withholds the main idea till the very end. In such sentences, the subordinate clause comes first. We tend to use loose sentences more than periodic sentences while conversing or writing. Here's an example to explain the difference between cumulative and periodic sentences: In the first sentence, the central idea (Stella is happy) appears first, followed by the additional information. In the second one, the main idea is delayed by providing the dependent clause first. The independent/main clause that comes in the beginning of the loose/cumulative sentence is a standalone sentence, whereas the periodic sentence begins with a dependent clause that will convey the complete thought, only after one reads the main clause at the end. It must be noted that a subordinate clause is not a standalone sentence, and the main thought of the sentence would not be understood till one reads the main clause that appears in the end. Thus, periodic sentences are more complex, formal, or literary in nature than cumulative sentences. Care has to be taken while structuring loose and periodic sentences. One has to be judicious when it comes to explaining the main clause through modifying subordinate clauses or phrases. At times, the reader might not want to read the entire sentence, as he/she feels that he's already aware of the main idea. If the sentence is too long, the reader might forget the main idea or lose interest by the time he/she comes to the end of the sentence. This also applies to periodic sentences. Though periodic sentences are complex and dramatic, they shouldn't be used too often. Some readers might feel impatient, when the central thought is delayed due to the long string of details. In the following examples, the central idea that is presented by the main/independent clause has been highlighted: In a periodic sentence, the dependent clause that provides additional information comes first, followed by the main clause (subject followed by the verb). Here are a few examples of periodic sentences: The aforementioned examples clearly indicate the straightforward nature of loose sentences. There is a reason why these sentences are used more often. They are simple, straightforward, and easier to understand. In cumulative sentences, the additional details may become quite important, as they clarify the main idea that is given briefly at the beginning of the sentence. However, periodic sentences can be quite emphatic. At times, delaying the central thought can increase its significance. Thus, you can use these sentences, when you need to keep the reader in suspense.