It is free, there are no licensing fees. Thus, fees for hosting solutions utilizing open source platforms are typically much lower.
Open Source Systems tends to be more reliable, efficient and stable than Closed Source ones. The widespread peer review process involved in Open Source development creates software that is more error-free and resource-efficient than proprietary software. Additionally, when issues arise, developer communities’ world-wide can put orders of magnitude more time into solving problems than their closed source counterparts.
Open Source Programming Solutions are usually much more platform friendly, in that they can be moved easily from one operating system to another.
Open Source Programming Solutions are usually much more hardware friendly, in that they can be moved easily from one type of hardware environment to another.
Security breaches are spotted sooner and closed more quickly.
The source code can be audited if the buyers/users don't trust the Open Source vendor.
The Negatives of Open Source
Because anyone can view the source, it is easier for the "bad guys" to find security holes.
Can lead to highly customized installations, which makes the learning curve for a new developer much higher, if the original implementer is no longer around.
