Each TNG episode has a specific name, normally quite a clever one that summarizes the main point of the episode. I was just wondering actually who the person was that gave TNG episodes their names?
The shows were named either by the showrunner, writing staff or (in the case of speculative scripts) the original writer or writers. There will often be input from the studio and other cast and crew.
The show may also go through multiple names before a final decision is made. "House of Quark" was originally "Fight to the Death" and "Unnamed Ferengi Episode", for example.
Although I've been unable to find a canon quote regarding Star Trek, this quote from Josh Malozzi, Senior showrunner for the Stargate series gives a pretty good overview of the normal decision-making process;
INTERVIEWER: How are episode titles chosen?
JOE: The hardest part of writing a script is coming up with the episode title. Either we'll come up with them individually or we'll say something in the room and someone will say, "Hey, that's a good title!" (i.e. "Going to Other Planets").