Why it's mostly using Dewey Decimal Classification?

DDC is an international recognished classification scheme .It is an alpha-numeric classification scheme which help to classify and asighn class no to documents easly. It is an enuemeratic classification scheme so most of the class no already mentioned.

DDC divides the knowledge into 10 main classes and 100 sub classes leading to 1000 divisions. which provide easy understanding for common users as well. it is based on arabic numerals which is very easy to memorize and use. 

it's a kind of Classification, that provides a system for organizing knowledge. Classification may be used to organize knowledge represented in any form, e.g., books, documents, electronic resources.

In the Dewey Decimal Classification, the notation is expressed in Arabic numerals. The notation gives both the unique meaning of the class and its relation to other classes. The notation provides a universal language to identify the class and related classes, regardless of the fact that different words or languages may be used to describe the class.

The system is further extended through number building, interoperable translations, association with categorized content, and mappings to other subject schemes.

Because it is simple to use what ever the library collections are small , medium or big.DDC is also suitable for general collections in schools and public libraries which occupy a big percentage from the total existing libraries.On the other side Library of congress classification is more suitable for speceialized libraries and collections like medical , engineering , legal libraries and so on..

To find out the location of book