Melvil Dewey was an American librarian and educator, best known for creating the Dewey Decimal Classification system in 1876. This system organizes library materials by assigning a unique number to each subject, making it easier for people to find books and resources. Dewey's work significantly influenced library science and education. In addition to his classification system, Dewey co-founded the American Library Association and established the first library school at Columbia University. His contributions helped shape modern librarianship and promoted the importance of accessible information for all. Dewey's legacy continues to impact libraries worldwide.