NBSI
NBSI - Not Blue Shoot It
This means: if a player's standing is not set above 0 (neutral), which makes the pilot "blue" (with a positive standing), you are supposed to shoot the pilot on sight.
The NBSI policy is the most popular security policy in use by corporations and alliances that operate throughout low security and 0.0 space throughout New Eden. Standings can be set at a Corporation or Alliance level to distinguish between friends and allies and everyone else.
When referring to the different non friendly entities, people without any standings set to them are typically referred to as "neutrals" while people with negative standings are referred to as Hostiles.
This is opposed to NRDS which means don't fire unless red (negative standing, or a red-flashy pirate).
NBSI and NRDS are the basic level of politics you decide to work on. Generally in lowsec a corporation or alliance will be either NRDS or NBSI in lowsec; and either NRDS or NBSI in 0.0.