Closed source is any software product to which a normal end user has no view into the source code of the product. Examples the Microsoft Operating Systems.
Open source software is any piece of software where a normal end user is granted a full view into the source code and has the option to modify this code for his or her own purpose.Examples Linux
Open Sourced software by definition, is any program or application that is freely distributed,non-platform specific and in which the programming code is open and visible.
*Large commercial vendors have, in theory, the resources to create quality assurance processes that include strict guidelines for programmers combined with design and code reviews to avoid security and reliability flaws from sneaking in. This is very expensive and may postpone the release of new products by weeks or months.
*It is cheaper to spend 200 hours fixing security and reliability problems found by customers than spending months fixing poor code which may or may not turn out to be a problem.
Commercial vendors have, in theory, the resources to respond very rapidly to severe reliability or security problems in their software. They should be able to provide manned contact points on a 24 by 7 basis.
*Often the license prohibits you from modifying the product. The fact that the source code is available for anyone to review does not instantly make the software free of design or implementation problems. If someone with the required knowledge sits down and reviews the product and feeds corrections back to the maintainer, it will help.
*When security problems are found in open source software, the fixes are often available within a matter of hours. Vendors of distributions that include the software can sometimes be much slower.
*Open source is the only real option...