What happened to the card catalog?

In years past when I lived in libraries (not literally), I spent huge amounts of time doing research. One of the most useful tools was to
read the card catalog. To do this, you needed the skill of flipping
through the cards very fast and also being able to read the information
in the split second the card was visible. The advantage of this type of
research was an overview of the target subject, with the result that I
often found valuable books or records I didn't know existed. Cataloging
books for libraries was partly science but mostly art. The cataloger
had to know what the book was about and decide about the assignment of
categories. Since the cataloger had a different perspective on the
information in the book or document than you did, you got a bonus look
at the information. At least two people's opinion about what might be
in the book.