Open Source Software

"The basic idea behind open source is very simple:

When programmers can read, redistribute, and modify the source code for a piece of software, the software evolves. People improve it, people adapt it, people fix bugs. And this can happen at a speed that, if one is used to the slow pace of conventional software development, seems astonishing.

We in the open source community have learned that this rapid evolutionary process produces better software than the traditional closed model, in which only a very few programmers can see the source and everybody else must blindly use an opaque block of bits.

Open Source Initiative exists to make this case to the commercial world.

Open source software is an idea whose time has finally come. For twenty years it has been building momentum in the technical cultures that built the Internet and the World Wide Web. Now it's breaking out into the commercial world, and that's changing all the rules. Are you ready?"

Quote from: OSI

What is OSS?

Open Source Software (OSS) is plain software, just like you know already. When in operation, you won't notice that the software is actually Open Source. The difference with its counterpart (proprietary software, also known as 'closed source software' or CSS) is the way in which it is licensed.

Both OSS and CSS come with a license that you have to accept and legally respect when using the software. It is this license that makes all the difference between OSS and CSS.

Where a Closed Source license often limits your ability to use or copy the software, an Open Source license explicitly gives you those rights. More specifically, it gives the right to copy, modify and distribute the software's original "source code". When a piece of software is licensed under an Open Source license, the software itself may be called Open Source Software, or Open Source for short.

For more details on available Open Source licensing, see http://www.opensource.org/docs/definition.php.

A universe of possibilities

The Open Source licensing scheme opens up a whole range of new possibilities. It is this range of possibilities that has motivated millions of people around the world with very different backgrounds to create, use or, in the case of policy makers, stimulate the usage of OSS.

For an overview of these motivations, see the "Many Aspects of Open Source".

OSS products

Over time a wealth of Open Source applications has been created, lots of which have become important market players. Examples are applications for desktop productivity, internet connectivity, software development and data storage and retrieval. These applications are often referred to as "horizontal applications" as they do not depend on the organisation in which they are used.

An overview of such applications can be found here, where you will see an extensive chart comparing well-known Windows applications with Open Source equivalents.

"Vertical applications", applications created for use in a specific market sector, have also been created. Examples are applications for handling Electronic Health Records (health care), school rostering (education) and applications for matching available jobs to personnel (employment and social affairs).

Quote from: European Commission OS Observatory