Prepositions link nouns, pronouns, and phrases to other words in a sentence. Common prepositions discussed include "on," "in," "at," "to," and "for." On is used for specific dates, days of the week, and locations like streets. In is used for years, months, seasons, parts of the day except at night. At is used for time, addresses, and other expressions involving time. To indicates movement or position and is used for addresses, offerings, and dedications. For indicates purpose, time, favor, or benefit.