A librarycatalog is a register of all bibliographic items found in a library.
A library catalog is a set of cards in the library that have information about the books, journals etc., written on them and are arranged in alphabetical order.
There are three types of library catalog: Author Card, Subject Card, and Title Card.
The author'sname is on the top line of an Author Card.
Author cards are filed alphabetically by surname.
The subject of the book is on the top line of a Subject Card.
Subject cards arrange all the library holdings by the main subjects of the title.
Subject cards contain information on how to find this book in the library, usually in the form of a specific callnumber.
The title of the book is on the top line of a Title Card.
Title cards contain the same information that the author catalog contains, but the information is rearranged on each card entry.
Title cards contain the author'sname, publishinginformation, and main subjects that may be found in the book.
An Online Public Access Catalog (OPAC) is an online bibliography of a library collection that is available to the public.
An Online Search Engine is a program that searches for words or phrases in documents, most often in articles, web pages and published materials on the internet.
Examples of onlinesearchengines are Google, Yahoo, Yandex, Aol, Ask, and Baidu.