" InWorldz originally started with the 0.6.5 version of the OpenSim code base, and modified it to make it more stable and resilient. But that version of OpenSim dates back to May of 2009. Since then, the OpenSim developers have improved the code substantially, first with a significant stability improvement in 0.6.9 (currently used by ReactionGrid and their client grids) and, last summer, with 0.7, which included a complete rebuild of the OpenSim architecture to make it more stable. In addition, 0.7 supports Second Life viewer 2, media-on-a-prim, and the more secure Hypergrid 1.5 protocol for teleporting between grids. Later, experimental versions of OpenSim even offer Second Life-compatible mesh support. By forking off from mainline OpenSim, InWorldz is now in a position to race to stay ahead of the army of open source developers working on improving OpenSim — and with each new custom developed feature, it becomes that much harder to switch back over to [or keep up with] the standard distribution of the software. Meanwhile, other grids are able to take advantage of OpenSim improvements without having to pay for any of the development costs that InWorldz has to incur."