The term wiki today is widely known as the technology behind such famous Internet sites as the Wikipedia. If you are not yet familiar with this technology you can consult this Wikipedia article.
MoStacks certainly is no convential wiki engine like e.g. MediaWiki that powers the Wikipedia. It isn't already for the simple reason that you cannot access a MoStack with a WWW browser, neither locally on your computer nor over the Internet. But nevertheless there are close similarities, and you can use MoStacks to build something like a wiki on your smartphone.
Wikis display pages that can have various formatting elements like paragraphs, links, and bold text. Normally quite powerful and complicated tools are necessary to produce such formatted pages, like Microsoft Word or Dreamweaver.
Fortunately wiki designers came up with a solution that it quite easy to implement: You write a wiki page as pure text, the source text, but add certain markup elements that the wiki engine interpretes and then formats the page accordingly when displaying it.
MoStacks implements a subset of a wiki markup variant called WikiCreole. The chapter Wiki Syntax explains all the supported markup elements.
The one element in MoStacks that is "wiki-enabled" is the field of type Text, with flag Wiki text? set (see Field and Control Flags: Wiki text). Such a field normally shows the formatted text after the wiki markup is interpreted, and you can not directly change the displayed text. You can look at and edit the source text including markup with the help of the Edit wiki function.
The fact that the content of wiki fields is still strictly textual has other benefits beside easy-to-implement and easy-to-handle editing. You can e.g use the CSV Import function to bring wiki content into a MoStack.
A page i.e. its background can contain any number of text fields with the Wiki text flag set, but a typical setup will probably work with a background that contains a single wiki text field that is as large as possible, like in the following screenshot:
Thus you don't declare a whole stack somehow to be a "wiki stack", but you just add as many cards with wiki text fields on them as needed to a stack, which of course can still contain any number of normal cards beside them. The stack is always a strict border, however: A wiki cannot span more than one stack.
The following table compares a typical Internet wiki with a MoStacks "wiki":
| Typical Internet Wiki | MoStacks Wiki | |
| Access | WWW browser over Internet | MoStacks client, locally on smartphone |
| Form of a wiki | a website | a stack |
| Unit of display | a page in the browser | a card with a wiki text field |
| Wiki engine | various, running on webserver | integral part of MoStacks client |
| Content store | database, running on webserver | part of a stack, as field values |
| Editing | in WWW browser, multi-user | in MoStacks client, single-user |
| Markup language | various | subset of WikiCreole |