The advent of ubiquitous computing has created a golden age for archaeological researchers and participating publics, but the price is a digital resource that is now in jeopardy. The archaeological record, in digital form, is at risk not simply from obsolescence and media failure, but the domain is also unable to fully participate in Open Data. Without swift and informed consensus and intervention, archaeology will lose the majority of its research data legacy and capacity to a digital Dark Age. It faces a number of challenges, distinct from those encountered in other domains:

1. Many forms of archaeological research (including excavation) destroy the cultural resource, and the recorded observations become the primary record, derived from non-repeatable documentation;
2. Archaeological data is often born-digital, and there are no paper surrogates for the primary record derived, for example, from the use of mobile devices on site, geophysical surveys or logging of experimental data by analytical laboratory equipment;
3. Archaeological researchers are particularly creative and innovative in their methodologies; adopting, adapting and developing novel techniques and approaches, and requiring stewardship of a wide range of data formats, and more complex understandings of data reuse, but often lacking the proper workflow and data policy found in other sciences.

In addition to the practical challenges described above, equally pressing is the lack of equity of access. Because archaeology has been an early and enthusiastic adopter of a wide variety of digital methods, most archaeological data, the result of decades of research funding, is being lost in most countries owing to a lack of appropriate persistent repositories with specialist knowledge (Wright and Richards 2018).

At the present time, only a handful of countries have repositories with the required specialist knowledge and mechanisms in place to ensure archaeological data will be freely and openly available for reuse by future generations of researchers. Failure to address this inequality means the world will be divided into countries and regions whose archaeological research legacy is preserved, and countries and regions where it is irrevocably lost.

This lack of equity also hampers participation in research collaboration. While best practice around the preservation and dissemination of archaeological data is well established in a few countries, most do not have persistently available data in interoperable formats. Many countries struggle to participate as partners in collaborative research projects, or to make their resources discoverable via European cultural heritage infrastructures such as Europeana and ARIADNE (Aloia et al. 2017).

Over the last decade, innovation has centred on making archaeological data more interoperable, both to increase the discoverability of data through integrated cross-search, and to facilitate knowledge creation by combining data in new ways. The emerging research challenge of the next decade is optimising archaeological data for reuse, and defining what constitutes good practice around reuse. This has been given a critical new framework through the recently developed FAIR (Findability, Accessibility, Interoperability and Reusability) Principles (Wilkinson et al. 2016), which will re-balance how research data is approached, making each principle of equal importance. This shift will create new opportunities for technological innovation and knowledge creation, but necessitates an interdisciplinary approach across stakeholder communities. To be successful, archaeology needs not only better policies for data curation, but also the harmonising of the processes of data creation and its deposition for archiving.

Only by bringing together the wide variety of stakeholders and decision-makers, from both the technology and archaeology domains, can these challenges be addressed. This includes representatives from countries, regions and institutions with all levels of experience and expertise; from a single archaeologist wanting to help build a new repository in their country to ensure data will be available and reusable for future researchers, to those from established archives working at a best practice and policy level to drive innovation and collaboration. By developing common understandings around the stewardship of digital archaeological data, building new support and best-practice networks and more inclusive research partnerships, progress can be made to save the archaeological research legacy from the digital Dark Age.

Over the last twenty years, and particularly within the last ten, archaeologists have become increasingly aware of the crisis surrounding digital data loss. In a few countries, archives have been created with a national remit, a specialist capacity to work with archaeological data, and adhering to international archiving standards. Within Europe, these archives include the Archaeology Data Service (ADS), based at the University of York in the UK, the eDNA archaeological repository of the Dutch Data Archiving and Networked Services (DANS), funded by the Royal Netherlands Academy of Arts and Sciences (KNAW), and the Swedish National Data Service (SND), hosted at the University of Gothenburg (not a dedicated domain archive, but able to handle the diverse data types used by archaeologists). In the United States, the Digital Antiquity consortium manages tDAR a repository hosted at Arizona State University.

However, there is increasing evidence emerging from international archaeology infrastructure projects, particularly ARIADNE, which created an infrastructure for the interoperable discovery of existing digital archaeological datasets across Europe, that this is a key moment to take action (Richards and Niccolucci 2019). The impact of the Open Data movement can be seen across all research sectors, with most national and international funders now requiring projects to make their data open within a specified timeframe, or carrying out testing of the viability of such requirements (e.g. the European Commission's Open Research Data Pilot). Many universities are also moving to implement similar requirements, but the task of archiving is often seen as the purview of libraries, which lack capacity to work with the wide variety of data formats created by archaeologists.

Outcomes from ARIADNE, Europeana and best-practice initiatives for cultural heritage such as Parthenos, DARIAH and E-RIHS have shown that a clear model is emerging with regard to international data stewardship. Data should continue to be held persistently at whatever local, regional or national level is appropriate, respecting existing legal parameters and intellectual property rights, while making the associated resource discovery metadata available to existing international infrastructures. This means resource discovery is not limited to a single infrastructure, and resources can be made interoperable in a variety of ways over time. It also means communities retain ownership of their digital cultural heritage legacy. As such, the need is not to create a new infrastructure for archaeology, but to build a network to support data stewardship at the local, regional and national level, and to support research capacity at a European and international level, creating better equity of participation in existing infrastructures.

Archaeology is not the only domain to struggle with data quality, reproducibility and lack of appropriate repository choices. Set out in 2016, the development of the FAIR guiding principles has changed the conversation around management and stewardship of research data, forming a holistic framework for optimising data, making each principle of equal importance. Archaeology is one of the leading proponents of Open Data in the arts and humanities, and already exhibits broad interest in FAIR, but the diversity of data types and methods used by archaeologists means adoption of FAIR will pose significant challenges, further necessitating urgent collaboration around best practice.

It was in this context that a proposal to establish a COST action was developed - a network of archaeologists and information scientists from Europe and beyond, aiming to share best practice and to build capacity for digital archiving in archaeology. The action was selected for funding from 2019-23 under the acronym SEADDA - Saving European Archaeology from a Digital Dark Age.

SEADDA has established four working groups, which broadly map onto the levels of development of digital archiving in the partner countries. Working Group One is focused on the first level of stewardship of archaeological data, aimed at partners who have recognised that they need to develop archiving capacity. Its first task has been to commence a survey of the state-of-the-art for preservation and dissemination in each country.

Participants came together at a workshop held in Gothenburg in November 2019, and each gave a presentation on the situation in their own country. This special issue of Internet Archaeology is the result. It comprises contributions given at that workshop, with others invited to fill in some of the gaps. In addition, we have welcomed a collaboration with the European Archaeological Consilium (EAC), which hosts a Working Group for Archaeological Archives long-involved in proposing standards in archaeological archiving (see Perrin et al. 2014). From 2018, the working group has focused its attention on digital archiving and SEADDA and the EAC have joined forces in presenting this report.

The articles in this special issue demonstrate significant differences in digital archiving capacity in different countries. In part these reflect differences in the history of archaeology in each country, its relationship to the state, whether it is centralised or decentralised, state-led or commercially driven. They also reflect some of the different attitudes to archaeology across the world, most recently explored in a survey conducted under the auspices of the NEARCH project (Kornelia et al. 2019). They reflect a snapshot in time, but our aim is to record the current state-of-the-art in each country, to inform knowledge, stimulate discussion, and to provoke change.