CLOCKSS is a collaboration of leading academic publishers and research libraries focused on the long-term preservation of digital scholarly content, having preserved 46 million journal articles and 260,000 books since its initiation by Stanford University 23 years ago. The partnership with Springer Nature, announced in January 2022, expanded the archive to include over 125,000 ebooks published since 1815. Effective digital preservation requires active management, diverse governance, and robust security measures.