is here defined as ”the extent to which the actual system delivers a surrounding environment, one which shuts out sensations from the ‘real world’, which accommodates many sensory modalities, has rich representational capability [...] ”. it implies also [sensory involvement] and [sense of presence]

The physical platforms upon which systems, facilities and networks are run. It enables connectivity and provides services via applications

Ownership of intangible information [...]. It is a legal framework that enables information to be owned and hence allows the owner to constrict its use or determine who uses it.

COPYRIGHT is one example of intellectual property.

An Interactive Virtual Museum is a Virtual Museum responding to a user's input [ref. Oxford Dictionary]. It includes [device-based interaction] and [gesture-based interaction]

Learning analytics is the measurement, collection, analysis and reporting of data about learners and their contexts, for purposes of understanding and optimising learning and the environments in which it occurs

According to “data.europeana.eu”, part of Europeana project, Linked Open Data is a way of publishing structured data that allows metadata to be connected and enriched, so that different representations of the same content can be found, and links made between related resources. Using a “cloud” platform it is possible to make the metadata available on the web using online services of data sharing and data retrieving.

In the context of virtual museums, “long-term” is not defined as a specific period of time. Also in the context of Digital Preservation, it is not strictly defined:  in (Verheuil 2006: 20) it means "five years or more", in (Research Councils UK 2008:6) "Data should normally be preserved and accessible for not less than 10 years for any projects, and for projects of clinical or major social, environmental or heritage importance, the data should be retained for up to 20 years, and preferably permanently within a national collection, or as required by the funder's data policy."

More generally in (CCSDS 2002: 1-11) "a period of time long enough for there to be concern about the impacts of changing technologies, including support for new media and data formats, and of a changing user community, on the information being held in a repository. This period extends into the indefinite future."

In the context of virtual museums, “long-term” is not defined as a specific period of time. Also in the context of Digital Preservation, it is not strictly defined:  in (Verheuil 2006: 20) it means "five years or more", in (Research Councils UK 2008:6) "Data should normally be preserved and accessible for not less than 10 years for any projects, and for projects of clinical or major social, environmental or heritage importance, the data should be retained for up to 20 years, and preferably permanently within a national collection, or as required by the funder's data policy."

More generally in (CCSDS 2002: 1-11) "a period of time long enough for there to be concern about the impacts of changing technologies, including support for new media and data formats, and of a changing user community, on the information being held in a repository. This period extends into the indefinite future."

a system communicating the content by means of low embodiment grade with the system or the environment like a descriptive application.

the ability of a Virtual Museum to be easily maintained and preserved (see [digital preservation]) for a [long time].

In hardware side it refers to the availability and capability of fixing any malfunction that can appear to the VM.

In software side it usually refers to the availability of updates, support, and compatibility with operating systems.

Regarding Content Maintenance, it includes activities “to ensure

• A robust computing and networking infrastructure

• Storage and synchronization of files at multiple sites

• Continuous monitoring and management of files

• Programs for refreshing, migration and emulation

• Creation and testing of disaster prevention and recovery plans

• Periodic review and updating of policies and procedures” (ALA 2007) 

Metadata are structured information about [digital objects]; they may regard specific cultural heritage object and their purpose and include description, management, resource recovery, preservation, curation and rights management, amongst other. 

Mixed reality (MR) (encompassing both augmented reality and augmented virtuality) refers to the merging of real and virtual worlds to produce new environments and visualizations where physical and digital objects co-exist and interact in real time. The term encompasses both augmented reality, where digital information and virtual objects augment images of the real world, and augmented virtuality, where real objects augment artificial computer-generated images co-exist.

According to Paul Milgram and Fumio Kishino the Virtuality Continuum extends from the completely real through to the completely virtual environment with augmented reality and augmented virtuality ranging between. In this context mixed reality  is defined as "..anywhere between the extrems of the virtuality continuum”.

is the act of deciding the location and/or orientation of a user or a physical object in 3D space 

A mode of communication in which the "Sender" provides information about events, monuments, artifacts, artworks, customs or beliefs by arranging them in a sequence (e.g. chronological), in order to create an account of a subject by the "Receiver's" side. As with exposition, narration includes description and interpretation and it may also rely upon/encompass some form of schematic representation (e.g. outline) of facts and figures.

Natural Interaction is a type of interaction that follows an approach to human-computer interaction which uses the natural behaviors (movement, gesture, speech) of the user to interact or "communicate" with an application. The interaction interface is meant to be invisible, or become invisible through naturalized interaction (requiring limited learning for interaction), and based on nature or natural elements [Blake 2010]. Ideally, natural user interfaces are designed to use natural human behaviours to interact directly with content, and may be facilitated with devices such as multi-touch surfaces (iPad or PixelSense) or motion detection sensors (Wii or Kinect). Bill Buxton, a Principle Researcher for Microsoft and pioneer in human-computer interaction has suggested that an interface is truly natural when it "exploits skills that we have acquired through a lifetime of living in the world" [Buxton, Bill 2010]. It includes [Free-form gestural UI] and [Speech-based interaction] 

It comprehends all Virtual Museums conceived to be not distributed, but only run in specific installations, according to institutional decisions

Assemblage of digital media providing the user passive (including emotional, intellectual and imaginative)engagement.