What is 'roleplaying'?
Roleplaying is the act of assuming the role of your character in-game, and acting as they would.
More broadly, 'roleplaying' is the act of writing about your created character and acting collaboratively with other like-minded players to create stories, either by acting as your character, or writing stories.
Here are some basic terms used for roleplaying.
IC - "In Character" - meaning that whatever text or act was meant to be seen as a roleplaying act -- it was done "in character".
OOC - "Out of Character" - the opposite of IC, this means that whatever was seen or heard was not meant to be seen as roleplaying.
LiveRP - this is roleplaying that is performed in the game with other players either watching or interacting. Examples of LiveRP might be a bar brawl, or the trial of notorious criminal.
rolenote - this is any entry on the 'roleplay board', which is where they should all go. Other players read these notes and get a clearer picture of other player's characters.