• alt.space - people and companies who believe that NASA, Boeing, Lockhed, Arianespace, and similar outfits are charging far too much for access to space and that we can, and should, get there much more cheaply, but have not made much progress because charging a lot is profitable and charging a little is not so profitable
• LEO - Low Earth Orbit, perhaps 200 km to 500 km above the surface.
• GEO - Geosynchronous Earth Orbit, some 36,000 km above
• ELV - Expendable Launch Vehicle
• RLV - Reusable Launch Vehicle
• SSTO - Single Stage To Orbit
• LOX - Liquid Oxygen
• NASA - National Aeronautics and ... look, if you haven't heard of NASA, you should go and read something else
• SDIO - Strategic Defense Initiative Office