Many users are unclear how RePEc works and how it differentiates itself from other services. This blog post tries to clarify in a succinct manner.
The core of RePEc is the metadata about the publications. The core is actually completely decentralized, and that metadata is compiled by the respective publishers and made available from their servers. There are currently over 2000 of those so-called RePEc archives. This means that publishers have full responsibility for their contents. The central core of RePEc is in fact just a set pointers indicating the location of the RePEc archives.
All that data is therefore freely available to anyone who wants to use it. Those are RePEc services that assemble all the pieces and make it available in various forms. For example, NEP sends emails about new papers, EconPapers and IDEAS allow to browse or search the data, or CitEc uses the data to try to extract citation data. The latter is an example of a RePEc service that enhances the data and makes it available to other RePEc services. A notable other example is the RePEc Author Service, which allows authors to create a compilation of all their works indexed in RePEc. These profiles are then reused by other services.