Moderate traffic situations:

Screening (or sweeping)
An aggressive car is attempting to pass on the right.  If it manages to do so, it will likely cut you off.  A slow-moving car is ahead in the passing car’s lane.  ‘Screening’ the passing car involves speeding up subtly to the point that it becomes impossible for the would-be passer to actually pass before being blocked by the slow-moving car.  The slow moving car has been used as a screen.  Screening should only be used to prevent reckless drivers from sweeping in front of you; screening another car simply to prevent him from getting around you is called ‘being a dick’ –don’t do this.  Screening can also be used as a means of breaking through a ‘Wall’ (see below) when a slow car blocking you on your right catches up to an even slower car.

Pulling
Sometimes you need to be in the space occupied by another car traveling in the same direction and at the same speed as you.  This could happen in a situation such as: you are attempting to exit a freeway and need to cross to the right lane, or you are at a two-lane stoplight and need to get over to the other lane to make a turn at the next stop.  In either situation it becomes necessary to ‘pull’ the other car out of the space you need to occupy.  To do this, accelerate heavily.  One of two things will happen: you leap past him and have free access to get in front of him (in which case pulling is not necessary) or you tickle his competitive spirit and he speeds up to block you.  In this case you have ‘pulled’ him out of his space.  Slow down quickly and slip in behind him, you are now free to exit the freeway, etc.

Hero
A ‘hero’ is a driver willing to drive much faster than the speed limit with no fear of police.  Waiting for a hero to pass and then following him allows you to travel faster than the speed limit and reduces the chances of your being caught for speeding.  The hero will be the first vehicle visible to a waiting police officer and is also an early warning system as his break lights will signal any police presence up ahead.

Eddies (swept up in the)
A fast moving car will increase the speed of all cars around it.  This is because slow moving drivers on American highways are only half awake.  They base their speed not on the speedometer but on to the cars around them.  If a fast moving car passes, it effectively resets their relative upper speed limit and they will speed up.  Much like the swirls of residual momentum created in fluids, these cars retain some of the speed imparted by the passing vehicle.  Naturally, after a few minutes or so, these cars will often slow back down (unless the passing car was only marginally faster, in which case they may become caught in his eddies perpetually). 

Out of (his/her) Element
When a driver has entered a fast-moving lane of traffic but is unwilling to keep up with the flow in that lane, he/she is said to be out of his element.  Such drivers are often necessarily passed on the right.

Wall
When two or more cars on a multilane highway travel side by side at the same rate, preventing any traffic from passing, they have created a ‘Wall’.  Often the driver in the fastest lane is ‘Out of his Element’.  Breaking through a wall is the only time it is acceptable to cut someone off.

Vortex (or vacuum)
On a two-lane highway when a slow moving truck occupies the right lane, traffic will preemptively vacate the lane, leaving a long unoccupied gap, or ‘vortex’ behind the truck.  Simultaneously, the left lane will be filling up and slowing down due to all of the additional cars merging into it.  An opportunistic driver may take advantage of a vortex by entering the right lane, speeding up and then merging back into the left just before reaching the slow truck.

Last in First Out (LIFO) rule
When a line of cars catches up to a slower moving obstacle (for example a large truck), the car in the back of the line has the first opportunity to move into a gap in the adjacent (faster-moving) lane and pass.  Once this car enters the gap, the gap has been filled, meaning the next car up the line must wait for a new gap.  Because of this rule you will often see one or two cars ‘stuck’ in the vortex behind any slow moving vehicle on a two-lane highway as new cars catch-up to, and then pass, them at a regular rate.

Los Angeles exit
Named after the city where it is most commonly observed, the LA exit is a maneuver that involves passing an exit on the freeway and then swerving over the widening double white lines in a last-second effort to make the exit.  The LA exit often involves kicking up dirt and debris and narrowly missing concrete barriers or plastic garbage cans filled with water.  Sometimes an overly optimistic driver gets stuck in the dirt and is said to be ‘lost in LA’

Stop and Go Traffic situations:

Exit Gap
The exit gap is a vacancy created in the right lane of a freeway between an exit and the following entrance.  This only occurs if the off-ramp is before the on-ramp. Cars exiting the freeway leave gaps that will be filled by new cars entering the freeway.  Sometimes the gap between off-ramp and on-ramp can be a quarter mile or more.  In high traffic situations this gap can be exploited. Just remember to get out of the right lane before you reach the incoming on-ramp traffic.

Accordioning
Slow moving traffic on a multi-lane highway follows a pattern of slowing and accelerating.  When the cars slow, they draw close to each other, packing in tightly.  When they accelerate, gaps form between them as some cars accelerate faster than others.  This pattern of opening and compressing is called ‘accordioning’.  Each lane of traffic often accordions at a different phase than its neighboring lanes.  An aware driver can anticipate when a lane is about to compress and switch to a different lane before it does.  Predicting this requires that the driver also determine the ‘true density’ of each lane.

True Density
The left-most lane of highway traffic travels at the greatest rate.  It also often contains the most cars, following the same principle as water pressure; a faster lane allows a greater density of cars.  When traffic suddenly comes to a halt (perhaps two highways are interchanging or there is an accident ahead) and all traffic is suddenly compelled to slow to the same speed, the true density will suddenly become painfully apparent.  The left most lanes will lock up and come to a halt long before the right-most lanes.  In these situations it is advisable to change over to the right lanes as soon as the breaklights become visible.

True density can also play a role in stop-and-go traffic.  Because all lanes are alternating stop and go on different phases, it is difficult to compare them directly.  Watching specific cars over a period of time can help you determine if one lane is trending slightly faster than another.  This will be because that lane has a slightly lower true density.