license sinatra 
A wiki is a website that provides collaborative modification of its content and structure directly from the web browser . In a typical wiki , text is written using a simplified markup language ( known as " wiki markup ") and often edited with the help of a rich - text editor . A wiki is run using wiki software , otherwise known as a wiki engine . There are dozens of different wiki engines in use , both standalone and part of other software , such as bug tracking systems . Some wiki engines are ___MASK34___ , whereas others are proprietary . Some permit control over different functions ( levels of access ); for example , editing rights may permit changing , adding or removing material . Others may permit access without enforcing access control . Other rules may also be imposed to organize content . A wiki engine is a type of content management system , but it differs from most other such systems , including blog software , in that the content is created without any defined owner or leader , and wikis have little implicit structure , allowing structure to emerge according to the needs of the users . XEmacs is a graphical - and console - based text editor which runs on almost any Unix - like operating system as well as Microsoft Windows . XEmacs is a fork , based on a version of GNU Emacs from the late 1980s . Any user can download , use , and modify XEmacs as ___MASK11___ available under the ___MASK31___ version 2 or any later version . GNU Emacs is the most popular and most ported Emacs text editor . It was created by GNU Project founder Richard Stallman . In common with other varieties of Emacs , GNU Emacs is extensible using a Turing complete programming language . GNU Emacs has been called " the most powerful text editor available today ." With proper support from the underlying system , GNU Emacs is able to display files in multiple character sets , and has been able to simultaneously display most human languages since at least 1999 . Throughout its history , GNU Emacs has been a central component of the GNU project , and a flagship of the ___MASK11___ movement . GNU Emacs is sometimes abbreviated as GNUMACS , especially to differentiate it from other EMACS variants . The tag line for GNU Emacs is " the extensible self - documenting text editor ". The ___MASK80___ is a permissive free software license originating at the Massachusetts Institute of Technology ( MIT ). As a permissive license , it puts only very limited restriction on reuse and has , therefore , an excellent license compatibility . The ___MASK80___ permits reuse within proprietary software provided that all copies of the licensed software include a copy of the ___MASK80___ terms and the copyright notice . The ___MASK80___ is also compatible with many copyleft licenses , such as the GNU General Public License ( GPL ); MIT licensed software can be integrated into GPL software , but not the other way around . Ruby on Rails , or simply Rails , is a server - side web application framework written in Ruby under the ___MASK80___ . Rails is a model  view  controller ( MVC ) framework , providing default structures for a database , a web service , and web pages . It encourages and facilitates the use of web standards such as JSON or XML for data transfer , and HTML , CSS and JavaScript for display and user interfacing . In addition to MVC , Rails emphasizes the use of other well - known software engineering patterns and paradigms , including convention over configuration ( CoC ), don ' t repeat yourself ( DRY ), and the active record pattern . Sinatra is a free and ___MASK34___ software web application library and domain - specific language written in Ruby . It is an alternative to other Ruby web application frameworks such as Ruby on Rails , Merb , Nitro , and Camping . It is dependent on the Rack web server interface . Designed and developed by Blake Mizerany , Sinatra is small and flexible . It does not follow the typical model -- view -- controller pattern used in other frameworks , such as Ruby on Rails . Instead , Sinatra focuses on `` quickly creating web - applications in Ruby with minimal effort . '' Some notable companies and institutions that use Sinatra include Apple , BBC , the British Government ' s Government Digital Service , LinkedIn , the National Security Agency , Engine Yard , Heroku , GitHub , and Songbird . Travis CI provides much of the financial support for Sinatra ' s development . Sinatra was created and open - sourced in 2007 . In computing , a web application or web app is a client  server software application in which the client ( or user interface ) runs in a web browser . Common web applications include webmail , online retail sales , online auctions , wikis , instant messaging services and many other functions . A domain - specific language ( DSL ) is a computer language specialized to a particular application domain . This is in contrast to a general - purpose language ( GPL ), which is broadly applicable across domains . There is a wide variety of DSLs , ranging from widely used languages for common domains , such as HTML for web pages , down to languages used by only one or a few pieces of software , such as Emacs Lisp for GNU Emacs and XEmacs . DSLs can be further subdivided by the kind of language , and include domain - specific " markup " languages , domain - specific " modeling " languages ( more generally , specification languages ), and domain - specific " programming " languages . Special - purpose computer languages have always existed in the computer age , but the term " domain - specific language " has become more popular due to the rise of domain - specific modeling . Simpler DSLs , particularly ones used by a single application , are sometimes informally called mini - languages .