How to look for a book in a library

A library is a room or building where we can read various types of books, journals, periodicals etc. and satisfy our thirst for knowledge. All of the books in a library are organized in some categories or classes and then arranged alphabetically within their classes. There are two systems for organizing books in a library. One is called the Dewey Decimal System and the other is known as the Library of the Congress System. Most of the libraries follow the Dewey Decimal System. Under the Dewey Decimal System, the books are grouped into ten major categories or subject areas. Each category is assigned a range of numbers and every book in the category is assigned its own special number within that number range. For instance, Science is assigned with numbers from 500 to 599. A particular science book can have a number such as 542.46 or 581.93. A science book would never have a number such as 800 or 200. The number that is assigned to a book is called call number. However, in this way books are arranged in a library. A library can offer us immense knowledge. So, we should visit a library regularly to enrich our depth of knowledge.