An Address Book is a tool used to store contact information for individuals and organizations. It typically includes names, phone numbers, email addresses, and physical addresses. Address books can be physical, like a notebook, or digital, found in smartphones and computers. Digital address books often come with additional features, such as the ability to categorize contacts, add notes, and sync with other applications. They help users easily manage their connections and quickly find the information they need, making communication more efficient in both personal and professional settings.