Plot Points

Plot points are awarded for IC and OOC things that make the game more fun for everyone. This can be anything from a really good joke that has everyone laughing. An awesome in character moment that is not heroic enough for a hero point. Doing something for the group, like bringing a snack, etc.
Another way to earn Plot point is to write up a place, person, item, or anything for the campaign world.  If it fits, I add it to the world to be there forever, and you get plot points.  
Plot points can be used to change the narrative of the game. To add some dressing for your character to use, to add a plot element that wasn't there. etc. Some example are below. They are not as powerful as hero points. They do not provide bonuses, but instead affect the actual story elements in many ways. As a rule, they shouldn't alter the adventure but some can depending on how cool an idea it is.

Examples: Adding a chandelier or something appropriate for your character to swing on, when it was not in the description. Changing the non-essential NPC a bit like making it an old friend, giving them a background that may tie in to yours, changing tier race or class to match an idea. (As long as it meets the narrative and doesn't change aspects important to the main storyline) Introducing a new element, like an old friend just showing up (Not to be used to save you in combat), or an event happening (party, funeral, etc), or a merchant being around the corners, etc. Anything else you can think of within reason that adds to the fullness of the world.