Editing Software (section)

===Licenses===
{{Main|Software license|Software copyright}}
[[File:Cube in Blender Editor.jpg|thumb|[[Blender (software)|Blender]], a [[free software]] program]]
Since the mid-1970s, software and its source code have been protected by [[copyright law]] that vests the owner with the exclusive right to copy the code. The underlying ideas or algorithms are not protected by copyright law, but are sometimes treated as a [[trade secret]] and concealed by such methods as [[non-disclosure agreement]]s.{{sfn|O'Regan|2022|pp=394-396}} A [[software copyright]] is often owned by the person or company that financed or made the software (depending on their contracts with employees or [[Independent contracting in the United States|contractor]]s who helped to write it).{{sfn|O'Regan|2022|p=403}} Some software is in the [[public domain]] and has no restrictions on who can use it, copy or share it, or modify it; a notable example is software written by the [[Federal government of the United States|United States Government]].  [[Free and open-source software]] also allow free use, sharing, and modification, perhaps with a few specified conditions.{{sfn|O'Regan|2022|p=403}}  The use of some software is governed by an agreement ([[software license]]) written by the copyright holder and imposed on the user. [[Proprietary software]] is usually sold under a restrictive license that limits its use and sharing.{{sfn|O'Regan|2022|pp=394, 404}}  Some free software licenses require that modified versions must be released under the same license, which prevents the software from being sold
or distributed under proprietary restrictions.{{sfn|Langer|2016|pp=44-45}}