LOD is an abbreviation for Lift Off Distance. When people refer to the Lift Off Distance of a mouse they are talking about the point at which the mouse stops tracking when picked up.
LOD in practice
Having a low Lift Off Distance might not be something that’s majorly important for people who play on a high sensitivity (since they won’t be lifting their mouse too often) but having a low LOD is pretty important for arm aimers or people with smaller pads.
When you’re gaming and you drag your mouse to the edge of your pad, you pick it up to put it back in the center in order to be able to move in all directions freely. The idea here is to do this quickly, so minimizing ‘travel time’ by not lifting the mouse unnecessarily high can save valuable time. If your mouse keeps tracking when you’re doing your ‘re-centering’ it will mess up the position of your ingame crosshair, which will obviously interfere with your ability to aim and can cause you to lose important fights.
It’s therefore mostly agreed on that a lower LOD (a ‘low LOD’ here means that the mouse stops reporting as soon as possible when it’s picked up) is better than a higher LOD.
Non-gaming mice can have a pretty high Lift Off Distance (going as high as a centimeter or more in some cases) so having the Lift Off Distance set much lower is just one of the many advantages that a real gaming mouse has over a regular office mouse.
The actual LOD can also vary depending on the surface you put the mouse on (a cloth pad, a hard pad, glass, …) so it is possible that the same mouse feels slightly different on a cloth pad versus a hard pad, for example.
LOD is often measured in ‘DVDs’ as these have a standard thickness of 1.2 millimeter. A mouse with a lift-off distance of ‘between 1 and 2 DVDs’ thus has an actual LOD between 1.2 mm and 2.4 mm. Some gaming mice also allow the LOD to be customized, either through software or through pressing a combination of buttons on the device itself.