Godmodding, (aka GM) as mention in the rules, is when someone controls characters that are not theirs, or makes references to things that their character should not know. Below are a few examples of Godmodding. Note that the colours represent different writers.
1) Reacting or responding to a character's thoughts or something that nobody else should be able to know (hidden feelings or something akin)
Brooke had a smile on her face as she sat by the side of the lake. She heard someone approaching, and turned to see who it was. Internally, she wished she had more alone time, but nevertheless, she kept the smile on her face and greeted the person who was there.
Travis had decided to take a walk by the lake. It seemed someone was already there, though, and as he approached her, he could tell she wasn’t happy about being disturbed. “I’m sorry for interrupting your alone time,” he said.
2) Stating the outcome of an action, unless previously discussed (a ‘permission to GM’ notice should be included in this case.)
Serafina took out her wand and quickly cast a stunning spell, hoping to disarm her attacker. It hit him in the face and she let out a mental cheer as he dropped his wand. She sent a body-binding curse his way, and smirked when it hit him and he fell to the floor, unable to move.
For the case above, you should not be controlling the results of your spell. You can, of course, indicate your intent. For example:
Serafina took out her wand and quickly cast a stunning spell, hoping to disarm her attacker. If it was successful, she would then send a body-binding curse his way. Mentally crossing her fingers, she hoped she would be able to stop him.
3) General controlling of a character, whether present in the thread or not.
Travis was out with his younger brother at an ice cream shop when he bumped into Braelynn. She smiled and greeted him, so he greeted her back.
Since I controlled what Braelynn was doing, this is considered GM. Note that NPCs count, especially if made by someone for a specific reason; for example, a relative or close friend to their character. For example, if Serafina has a NPC younger sister named Stephanie, you would have to ask the person who writes Serafina for permission before writing using Stephanie, even though Stephanie doesn’t have a character profile.