What are the ten classification of Dewey decimal system?

The Dewey Decimal System (DDC) has 10 main classes, not 10 classifications. These are represented by the first digit of the call number:

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 Geography and history

Within each of these main classes, there are further subdivisions and specific call numbers to pinpoint the exact subject.