A living document or dynamic document is a document that is continually edited and updated. A simple example of a living document is an article in Wikipedia, an online encyclopedia that permits anyone to freely edit its articles, in contrast to "dead" or "static" documents, such as an article in a single edition of the Encyclopædia Britannica.
A living document may or may not have a framework for updates, changes, or adjustments. This type of document without proper context can change away from its original purpose through multiple uncontrolled edits.
This is different than an evergreen document that is written in a way that is relevant to a specific audience over a long period of time, and does not change. This relevance comes from a universal acceptance or application of document contents.
However, a living document may evolve through updates, be expanded as needed, and serve a different purpose over time. Living documents are changed through revisions that may or may not reference previous iterative changes. The rate of document decay depends on the structure of the original document, or original intent of such document, or guidelines for modifying such document.
In law 
In United States constitutional law, the Living Constitution, also known as loose constructionism, permits the Constitution as a static document to have an interpretation that shifts over time as the cultural context changes. The opposing view, originalism, holds that the original intent or meaning of the writers of the Constitution should guide its interpretation.
The claim that the US Constitution is a living document is often made by partisans who disagree with some parts of it. This is most often because they disagree with specific freedoms enumerated in the Bill of Rights.
In business 
In business a living document may fall under corporate change management or be shared among a team. It may start as a draft work that at some time graduates into general acceptance, or may originate as part of a formal documentation process. Regardless of the degree of formality, a living document needs rules or guidelines for its modification. Such guidelines allow — and should ideally encourage — the document's evolution over time. It is in this sense of growth that the document can be thought of as "living."
In pastoral theology 
In pastoral theology the 'living document' refers to an individual person.