Open source is frequently cited as one of the most important movements in modern software creation. It is supported by the European Commission, Governments, institutions and almost every further and higher education institution makes use of open source software.

What is Open Source Software?

'Open source' describes computer software for which:

• source code is available to the end-user
• source code can be modified by the end-user
• there are no restrictions on redistribution or use
• licensing conditions are intended to facilitate continued re-use and wide availability of the software, in both commercial and non-commercial contexts.

In every other respect there is no difference between this and conventionally-licensed software. The key differentiator is the licence. The term 'open source' is reserved for licences, which are certified by the Open Source Initiative (OSI) to meet the criteria of the Open Source Definition (OSD).

Licences

Presently, there are in excess of 50 OSI certified open source licences. The following five are perhaps the most commonly used:

• Apache Licence
• GNU General Public Licence (GPL)
• GNU Lesser General Public Licence (LGPL)
• Modified BSD (Berkeley Software Distribution) Licence (new BSD)
• Mozilla Public Licence (MPL)

The difference between them is the extent to which they control the way the code can be combined with other software. At the one extreme, the BSD licence permits open source software to be merged with closed-source code and then sold under a conventional licence. At the other, the GPL licence insists that if the software is combined with other code then that too must be under a GPL licence.

Open Source Use

Interoperability is often declared as the principal reason for considering the deployment of open source software. This is because open source development tends to support open standards. Additional factors that can give open source deployments an advantage are:

1. No licence surprises. Open source licences are free and perpetual, so a licence fee increase cannot happen.
2. No incentive for theft. With open source software people can use and copy the software legally.
3. The lack of secrets. The working of the software is available for anyone to inspect, something of great importance for security auditing.
4. The ability to tailor the system completely to local needs. Both open and proprietary software are typically customisable in a shallow sense - institutions can tailor the interface within the bounds given by the programmers. With open source, if an institution needs the software customised in ways not thought of by the programmers, they can have the program changed, either in-house or by a third party.

Common Misunderstandings about Open Source

Open source software is often confused with other software whose minimal cost of acquisition makes it appear similar:

• Software, which can be freely redistributed, but without source, or the right to modify or redistribute it; again, such software does not have an open source licence.
• Software, which follows the open source guidance, but whose licence has not been accepted by the OSI: open source is not achieved by self-certification.
• Software released with source under special conditions, such as not allowing commercial use; this contravenes one of the fundamental criteria of the OSD.

References to Open Source Initiatives

Apache: http://www.apache.org/

Globus Alliance: http://www.globus.org/

Linux Red Hat: http://www.redhat.com/

Open Source Definition: www.opensource.org/docs/definition.php

Open Source Initiative: http://www.opensource.org/