system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: The political situation of the galaxy in the Star Trek movies

So I'm looking forward to the new Star Trek movie coming out this week, but rewatching the first one yesterday I realized that I didn't really know much about the background of the setting. I know we have humans, Vulcans, Romulans, and Klingons, but I don't really know which races are part of the Federation, which ones are at war, any of the history, etc. I heard reference to a "neutral zone" in the movie yesterday, but I don't know the context. Somebody want to give me an overview?
gpt
In the J J Abrams movies the three major factions are the Federation (Humans, Vulcans, other friendly aliens), the Klingon Empire, and the Romulan Empire.

Klingons are combat-oriented aggressive aliens.  Romulans are sneaky clever spy aliens.  Klingons and Romulans are sometime allied with each other, but more often not.

The neutral zone is a "border" between the three government's districts in space.  When a ship from any side enters the neutral zone, it is seen as a provocation so a lot of stories deal with these border squabbles.