Latency is how fast data is moving. How quickly does it get from point A to point B? (And it’s generally measured in milliseconds.)
Tick rate is how often a game refreshes its information. Usually, it’s measured in hertz. For example, a 128-tick server will update 128 times a second. Not to be confused with FPS (frames per second). This is how things are rendered on your screen per second.
A high tick rate is essential for multiplayer games, particularly first-person shooters. Most FPS games need a tick rate of at least 64. Any lower, and the server probably won’t keep up with the action.
Your matchmaker decides which players to group up for a session. It grabs information from each player and then runs it through a set of rules to figure out the best possible match.