Open standards allow a user to be platform, vendor and software independent. Standards make networking possible, and make it easier to upgrade and move customised software solutions from one platform to another.
Access to technology at the source
Open source has also allowed and encouraged research and development laboratories in academia, public service and commercial industries to gain access to technologies that might otherwise be prohibitively expensive, which in turn has led to increased participation and feedback.
For instance, GNU/Linux and open source have led the field in clustering and virtualisation technologies, which were initially developed from academic research. (A side effect of this is that Linux has revived the market for the mainframe).
For similar reasons many smaller startups - as Google once was, for example - have based their operations on the use of free software. It is doubtful that Google would have been as successful as it has, had the company not been able to customise Linux and the Google filesystem on clustered servers to build its original search and storage algorithms.
For the company deciding to come over to Linux cost may be the initial motivation. Software is a tool, and not the final objective of the company. There is an over-riding interest in having software that "just works" at reasonable cost, and this is where GNU/Linux comes into its own.
Freedom
Most advocates of free software would claim that freedom, "not as in beer, but as in spirit", is the principle advantage and purpose of open source, and from this principle emerge all the other benefits of free software.
In the words of Richard Stallman "free software is a matter of the users' freedom to run, copy, distribute, study, change and improve the software." More precisely, it refers to four kinds of freedom, for the users of the software:
"The freedom to run the program, for any purpose (freedom 0).
The freedom to study how the program works, and adapt it to your needs (freedom 1). Access to the source code is a precondition for this.
The freedom to redistribute copies so you can help your neighbor (freedom 2).
The freedom to improve the program, and release your improvements to the public, so that the whole community benefits (freedom 3). Access to the source code is a precondition for this."
