The word "my" is a possessive adjective used to indicate ownership or association. It is commonly used in the English language to show that something belongs to the speaker. For example, in the phrase "my book," the speaker is indicating that the book is theirs. In addition to indicating possession, "my" can also express a personal connection or relationship. It is often used in contexts involving family, friends, or personal belongings, such as "my sister" or "my car." This word helps to convey a sense of intimacy and personal relevance in communication.