Generally somewhere between 250-300 km (where air drag starts to become important) and 1000 km (where the inner van allen radiation belt Eric Weisstein's World of Astronomy starts to get serious). Low earth orbit usually implies a modest inclination to the equator, (i.e., the lowest achievable from the launch site). The Space Shuttle flies in low Earth orbit.
Geosynchronous Orbit, High Earth Orbit
