Exchange Server user load: The amount of stress placed on an Exchange Server computer by one or more LoadSim clients simulating multiple LoadSim users based on a particular user profile.
LoadSim: The Exchange Load Simulator software.
LoadSim client: The machine that runs the LoadSim software. This client machine must have the Microsoft Exchange Client software installed.
LoadSim user: One synthetic Exchange user that LoadSim creates and simulates. You usually run multiple LoadSim users on a LoadSim client.
LoadSim user profile (or user type): The type of Exchange user, whether it is a heavy hitter or one that hardly uses the system. Three predefined profiles exist in LoadSim: Light, Medium, and Heavy. I use the terms profile and type interchangeably.