This article provides legal definitions, recommendations, and best practices for cultural, scientific and memory institutions to constitute, manage, and distribute public domain collections. Public domain, in the strict sense, is the legal state of cultural, scientific and literary works and data when copyright does not subsist, meaning they can be freely accessed and reused without asking for permission, or paying any remuneration. Memory institutions designate public service and university libraries, archives, museums, but also private galleries and volunteer-based projects such as Wikipedia, acting as de facto memory institutions as their mission is to collect, process and disseminate archives to the public.  Other cultural and scientific institutions in charge of curating public domain collections can include primary education, research bodies, universities, broadcasting organisations. These policy recommendations are anchored in European law and framed through the normative perspective of the preservation of the public domain under open terms:  “No other intellectual property right must be used to reconstitute exclusivity over Public Domain material” (Communia Public Domain Manifesto 2012, following Boyle 2009). Following each of the five steps defined by the scientific editors of the book  allows to structure the delivery of practical advice and “things to think about” to support the successive copyright-related tasks leading to the creation of an online archive. The article is composed of four parts: core legal definitions following the actions and steps of archiving (1), more legal definitions around rights which need to be licensed (2), a presentation of open licenses which can be used (3), and a discussion of institutional policies and issues faced by memory institutions, being galleries, libraries, universities, museums, or archives as well as public, commons-based, or private institutions in the process of creating collections of a variety of works (4).