Grammarians sometimes categorize sentences as "loose" or "periodic."

Although "loose" used to be a fairly common term for an immoral person, to grammarians it means something entirely different.

A periodic sentence is one that keeps the reader waiting until the end (the period, or other mark of terminal punctuation) before the meaning becomes clear.  Examples: 1) The salesman, after much hemming and hawing about the car's superior features, finally answered my question about the price. 2) Snowstorms, hurricanes, tsunamis, freak storms—all these may result from our unconscionable tinkering with the atmosphere.

A loose sentence is simply one that is in so-called "normal" or "standard" order:  subject, verb, and (if there is one), complement. Most of our sentences are loose, and that's a good thing—they're more likely to be clear and easy to read. Of course, we want to use some periodic sentences, when they suit our purpose (e.g., emphasis, sentence variety). But they can be distracting, so are to be used with care.

It's not all that important to know the names of these categories—the terms aren't often used, even by English teachers. But it is important to avoid too many of one kind—especially periodic sentences.