Over on the Second Life educators mailing list, a member asked for an 'Idiot's Guide to Second Life'. I wrote a reply there, which seemed like it might be a useful post here as well.

OpenSim is a project to create software so that others can create their own servers that run similar to Linden Lab's Second Life servers.

Typically, people running OpenSim set up a grid, similar to the Main Grid, the Teen Grid or the Beta Grids that Linden Lab runs.

Some example grids like this are:

Central Grid has about 20 regions and about 1,400 active members. They are focusing hard on the business community.

OpenLife has nearly 200 regions and a population of over 20,000. They support the RealXtend viewer.

OSGrid claims 240 Regions and 2400 active users. They are running as a non-profit.

When you use a Second Life client, you can specify a parameter to get your client to connect to one of these other grids. (e.g.
"C:\Program Files\SecondLife\SecondLife.exe" -multiple -loginuri http://osgrid.org:8002 )

If you have a reason to, you could create your own Grid that you control, e.g.

Orient Lodge Grid

In the old days of MOOs, this was a common thing. People would set up their own MOOs for their universities, or any other place they wanted. I ran LogMoo, which is actually still sitting around in mothballs. When I get a better Internet Connection, I may bring back LogMoo and perhaps setup LogGrid.

As a general rule, there is essentially no connectivity between grids. Just as it is at best very difficult to move stuff from TeenGrid to the MainGrid, etc., it is very difficult to move stuff to the any of the OpenSim based grids.

There are a few interesting exceptions.

SecondInventory now supports OpenSim. What this means in theory as that you can create something on one grid, say the Main Grid, or an OpenSim grid, and then restore it to other grids. I've had limited success with that, that it looks very promising.

For communications between grids, there has been some work done on using IRC channels so that a space in the main grid could listen and/or talk on an IRC channel and a space in an OpenSim grid could listen and/or talk on the same IRC channel. I've heard this discussed, but I don't know anyone who has done this in practice. I think this fits in nicely with the talk about Twitter as well.

The folks at Central Grid have been working hard to get currency working in OpenSim, including working with a company to do intergrid currency exchange. I believe it is still in development, and it raises a lot of issues. Most notably, some of the folks behind Central Grid have been accused of being scammers on the Second Life main grid and people have expressed skepticism about financial transactions on any OpenSim grid.

It is also possible to run a portion of OpenSim so that you run just a region and that region becomes part of another groups grid. Some of the OpenSim grids discussed above have been exploring allowing remote regions to be part of their grid. I'm not sure how well that has worked yet. You can also run a region without it being part of a grid. I've done that from my laptop when I wanted to have a small Second Life environment that I could bring with me.

As a final note, Open Sim is still in early development. Unless you are pretty geeky and like playing things that might break even more frequently than the Linden Lab Main Grid, you might want to leave Open Sim to others. I'm a hard core geek, so I love OpenSim.

Okay. Perhaps that was a little bit longer and geekier than a true idiots guide to Open Sim, but I hope it is helpful.