A simple sentence is the most basic way of patterning words together to communicate a thought. It has three items, usually in this order:
1. a subject (someone or something performing the action, a noun or a pronoun)
2. a verb--an action word (such as "ran," "decided," or "snowed") or a state of being word (such as "to be" or "to feel"), and
3. words to complete the thought.
Note that the term "simple sentence" refers to a sentence pattern (and not to the complexity of thought in the sentence).
Simple sentences provide the most usual way of communicating in written English. Very short, simple sentences also can be used to emphasize ideas when inserted in a paragraph of longer simple, compound, and complex sentences.
Although the mist in the air had turned to sleet mixed with snow, Alice decided to chance going out, since she needed some supplies for dinner. She skidded into a parking spot at the supermarket, slipped when getting out of her car, and carefully made her way inside. She chose broccoli and potatoes for the cream soup that she had planned, and decided to splurge on real cream instead of the skim milk that was already in her refrigerator. She completed her shopping and stood in the checkout line. Then it hit her. She had neglected to take her purse.