Types of Card Catalog?

In ‘ancient’ times before computers were the dominating source of information and accuracy, libraries used a card catalog system to help people find books easily. This card catalog system was inclusive of a single card, that had all of the information about a book written on it, and gave the book a call number so that it can be easily located within the bookshelves of the library. In modern times, while a library may still have a card catalog system that utilizes index cards for informaion, a library may also have their card catalog system online, this is another type of card catalog.