If there are 3 lanes on your side of the freeway, the right-hand lane is there for vehicles to merge onto the freeway and it is the place for slower moving vehicles to drive; such as big rigs or cars towing anything. The lane in the middle is the passing lane for slow moving traffic, and it is the lane for primary travel of other than slow moving vehicles. The lane to the far left is for passing only, except when designated for specific use, like a carpool lane.
you should safely change to the right lane
Merge into the nearest left lane when it is safe to do so.
in the center lane
Drivers intending to stay on the highway/freeway should stay in the right lane or the lane designated as a through-lane. The only times you should move left is to allow vehicles to merge from a right side on ramp (and move back to the right lane as soon as you can), or to pass slower traffic already in the right lane (then move back to the right lane when it is safe to do so). If a freeway provides a "slower" lane and you drive slower than the maximum speed allowed, you should use the slower lane. But never hog the passing lane just to keep driving in it; move over and let faster traffic pass you.
The rules for using the fast lane on the freeway are that it is meant for passing other vehicles and should not be used for cruising or driving at a slow speed. It is important to move back to the right lanes after passing to allow faster-moving vehicles to pass. Additionally, it is illegal to drive in the fast lane if you are not passing another vehicle.
HOV lane (High Occupancy Vehicle) 2+ passengers must be in the vehicle while driving in said lanes.
The left most lane
When driving on a four lane highway or freeway you should use the right hand land or 'thru lane' except when passing. If the right hand lane is designated for slower traffic or for exiting traffic, you'd use the lane to the left of it.
If you are referring to a freeway division (as in on the road), the answer is "lane." (:
SAFELY merge into and through the slower lanes of traffic. If you cannot do so before your exit is reached, continue on the next exit by driving in Lane 4 - exit there and then return one exit to your original destination.
On a freeway/highway, the lane which contains the diamond like shape is a separate travel lane. Specifically this lane is dedicated to the "ride share" and/or individuals carpooling.
The purpose of the fast lane on a freeway is to provide a designated lane for vehicles to travel at higher speeds, allowing for smoother flow of traffic and passing of slower vehicles.