Punctuation marks are symbols used in writing to clarify meaning and indicate pauses or stops. Common punctuation marks include the period, comma, question mark, and exclamation point. Each mark serves a specific purpose, such as ending a sentence, separating items in a list, or expressing strong emotions. Using punctuation correctly helps readers understand the intended message. For example, a comma can change the meaning of a sentence, as in "Let's eat, Grandma!" versus "Let's eat Grandma!" Proper punctuation is essential for clear communication in both formal and informal writing.