SECURITY STATUS
When you kill a player's ship, (and more seriously his pod) you receive a security rating drop. This can only be raised by killing battleship npcs, which is probably way above you at this point. Dont worry, if yu want to be a true pirate, you can worry about this later: just make sure you dont get trapped in a low security system surrounded by a lot of high security ones, as you may find it hard to get out. Once you reach -5.0 you can be shot ANYWHERE without penalty, so be aware.

Security ratings:
-1.9 and above: you can enter all space freely
-2.4 and above: you can enter all but 1.0
-2.9 and above: you can enter all but 0.9 and above
-3.4 and above: you can enter all but 0.8 and above
-3.9 and above: you can enter all but 0.7 and above
-4.4 and above: you can enter all but 0.6 and above
-4.5 and below: you cannot enter secure space without being fired upon by the navy/concord