This lesson explains the use of the apostrophe in English. Apostrophes show possession (e.g., “Ali’s book”), form contractions (e.g., “it’s” for “it is”), and are sometimes used for plurals in special cases like letters or numbers. It covers rules for singular and plural nouns, compound nouns, joint and separate ownership, and common mistakes, such as confusing “its” and “it’s” or using apostrophes for normal plurals. The lesson also explains apostrophes in time expressions and provides practice exercises, worksheets, and quizzes to reinforce proper usage in writing and speaking.