The Dewey Decimal System (DDC) is a system of library organization developed by Melvil Dewey in 1876. It is a hierarchical system that assigns a unique number to each book, based on its subject matter. The DDC is used by libraries all over the world, and it is the most widely used library classification system in the United States.
The DDC consists of ten main classes, which are further divided into subclasses and sections. The ten main classes are:
1. 000 - Computer science, information, and general works
2. 100 - Philosophy and psychology
3. 200 - Religion
4. 300 - Social sciences
5. 400 - Language
6. 500 - Pure science
7. 600 - Technology
8. 700 - The arts
9. 800 - Literature
10. 900 - History and geography
Each main class is further divided into ten subclasses, and each subclass is further divided into ten sections. This allows for a very specific classification of books, so that readers can easily find the books they are looking for.
For example, a book about the history of the United States would be classified as follows:
900 - History and geography
970 - History of North America
973 - History of the United States
Library of Congress
The Library of Congress (LC) is the largest library in the world, with over 170 million items in its collection. It is located in Washington, D.C., and it is the research library for the United States Congress. The LC also serves as the copyright office for the United States.
The LC uses its own classification system, which is called the Library of Congress Classification (LCC). The LCC is a more complex system than the DDC, and it is used by research libraries all over the world.
The LCC consists of 21 main classes, which are further divided into subclasses and sections. The 21 main classes are:
1. A - General works
2. B - Philosophy, psychology, religion
3. C - History, auxiliary sciences
4. D - History and topography (except America)
5. E - America
6. F - Political science
7. G - Geography, anthropology
8. H - Social sciences
9. J - Political science
10. K - Law
11. L - Education
12. M - Music
13. N - Fine arts
14. P - Language and literature
15. Q - Science
16. R - Medicine
17. S - Agriculture
18. T - Technology
19. U - Military science
20. V - Naval science
21. Z - Bibliography, library science
Each main class is further divided into subclasses, and each subclass is further divided into sections. This allows for a very specific classification of books, so that researchers can easily find the books they are looking for.
For example, a book about the history of the United States would be classified as follows:
E - America
E1 - History of the United States: General & comprehensive works
The DDC and the LCC are the two most widely used library classification systems in the world. They are both hierarchical systems that assign a unique number to each book, based on its subject matter. The DDC is more commonly used in public libraries, while the LCC is more commonly used in research libraries.