According to opendefinition.org, a work is open if its manner of distribution satisfies the following:
Access: The works shall be available as a whole and at no more than reasonable reproduction cost, preferably downloading via the internet without charge. The work must also be available in a convenient and modifiable form.
Redistribution: License shall not restrict any party from selling or giving away the work either on its own or as part of a package made from many different sources. The license shall not require a royalty or other fee for such sale or distribution.
Reuse: License must allow for modifications and derivative works and must allow them to be distributed under the terms of the original work.
Absence of Technological Restriction: The work must be provided in such a form that there are no technological obstacles to the performance of the above activities. This can be achieved by provision of the in an open data format, ie. one whose specification is publicly and freely available and which places no restrictions, monetary or otherwise upon its use.
Attribution: The license may require as a condition for redistribution and re-use the attribution of the contributors and creators to the work. If this condition is redistributed without the need for execution of an additional license by those parties.
Integrity: The license may require as a condition for the work being distributed in modified form that the resulting work carry a different name or version number from the original work.
No discrimination against fields of Endeavor: The license must not restrict anyone from making use in a specific field of endeavor. For example, it may not restrict the work from being used in a business or from being used for university research.
Distribution of license: The rights attached to the work must apply to all to whom its redistributed without the need for execution of additional license by those parties.
Primary permission or usage rights where open content is concerned
1: Reuse: The rights to reuse the content in its unaltered/verbatim form(e.g. make a backup copy of the content)
2: Revise: The right to adapt, adjust, modify, or alter the content itself e.g. translate the content into another language).
3: Remix: The right to combine the original or revised content with other content to create something new (e.g. incorporate the content into a mashup).
4: Redistribute: The right to share copies of the original content, your versions, or your remixes with others (e.g. give a copy of the content of a friend)