1 What
is open source software?
The
definition of open source
For
OSS Watch, open source software is software that has been released under an
Open Source Initiative (OSI) certified licence. OSS Watch uses this
OSI-approved list as a means of avoiding debates over interpretation of the
open source definition and which licences do or do not conform to it. By
recognising the OSI as the appropriate final authority in this issue, much
confusion is avoided.
Each
of the licences approved by the OSI meets the conditions of the Open Source
Definition.
That definition includes 10 criteria. Perhaps the most important of
these are the free redistribution of the software, access to the source code,
and the permission to allow modifications to the software and derived works
that may be distributed under the same licensing conditions.
Very
different styles of licence meet these criteria. The GNU General Public
License, commonly known as the GPL, meets the criteria. The MIT licence, which
is very different in length and intent from the GPL, also meets the criteria.
Indeed, around 70 licences have gone through the approval process. To help with navigating through these
licences OSS Watch has produced a series of documents that describe some of the key licences in
plain English.
For
an individual or project looking to license their code, using an OSI-approved
licence can simplify the process. In fact, many people (including OSS Watch)
do not consider software to be open source unless it is released under an OSI
approved licence. For potential contributors and users who wish to work with
open source, it provides a quick way to check that the code is indeed open and
accepted by a large community.
Is open source ‘only’ a licence?
The
expression open source has wide application. For the OSI it also refers
to the distinctive software development methodology employed by many open
source software projects. The OSI home page starts with ‘Open source is a
development method for software that harnesses the power of distributed peer
review and transparency of process.’ However, the OSI stops short of defining
this methodology in the Open Source Definition, which concerns itself only with
the requirements of a licence designed to protect this way of developing
software.
The
open development
methodology is based on principles that may not be among the principles
of software development normally taught in academia. Open source software,
strictly speaking, may or may not be developed using an open development
methodology. The choice of which development methodology to adopt is dependent
upon a project’s chosen route to sustainability.
Does open source mean anything else?
The
term ‘open source’ originated in the worlds of journalism and intelligence, and
referred to a publicly available source of information. This former use was
known to the founders of the Open Source Initiative, and was felt to be ‘a feature, not
a bug.’
Sometimes open source is conflated with open
content or free content. Open content refers to content that can be
edited, changed and added to by any reader. A good example is the famous Wikipedia,
an online open content encyclopaedia. Open source is used today in various
contexts which take it far beyond its application in software. However, to
re-state, for OSS Watch open source software always refers to software released
under an OSI-certified licence.
Is open source software the
same as ‘free software’?
Free software is an expression used by
the Free Software Foundation.
The term ‘free software’ pre-dates open source software, and focuses on several
kinds of
freedom that are associated with the software, thereby taking a more
ethical viewpoint on the matter. For some, it is the preferable term
and they do not wish to associate themselves with the term open source. Free
software must not be confused with ‘freeware’, which is software that can be
acquired at no cost but for which source code may well not be available.
When we at OSS Watch use the term open source
software without a more specific qualification, this will usually include both
Free and Open source software. A common abbreviation for this collection of
software is FOSS.
Further reading
Links
- The Free Software Definition
Related
information from OSS Watch
