Web platforms may one day catch up to traditional institutions like the Library of Congress in their ability to collect and organize millions of documents, according to an infographic by content curation platform Scoop.it.

Technology is influencing traditional libraries, too. In January, the Library of Congress was looking for ways to make digital archives more searchable after Twitter gifted the national library with access to its own historical data.

In this overview of four internet companies — Quora, Wikipedia, Scribd, and Scoop.it — the authors explain how each site’s approach to indexing knowledge corresponds to the way that libraries preserve information and how much they’ve collected so far.