Ability to read defenses

Question
Hello- we have the same names and my last name starts with a B also....

My question really may not be actually 1 question. I'm trying to get an understanding of how a QB reads a defense in a passing situation. I've heard the term "progression" used as something the QB needs to do when he reads the defense. Exactly what is progression?

My second question may be directly tied to my first one, and I hope its not too general. I do know that if a WR goes in motion and the CB follows, that is an indication of man coverage. When the CB does not follow that is a zone defense. How do the safeties and LBs react in man and zone coverages? Do they tend to backpeddle, or run at their man? Quarterbacks have very little time to make a decision on who and where to pass the ball. I'm trying to educate myself on what the QB is supposed to "see" and "read" that will in turn make them throw the ball to the proper receiver.

I eagerly await your reply on this. Thank you for being available to answer these questions.

Answer
ALWAYS GOOD TO GET A QUESTION FROM A BRIAN.  TO ANSWER YOUR FIRST QUESTION, A PROGRESSION READ IS PRETTY SIMPLE.  MOST SOPHISTICATED OFFENSES USE PROGRESSION READING IN THEIR SYSTEM.  IT GENERALLY CONSISTS OF THE OFFENSIVE PLAY ATTACKING ALL THREE LEVELS OF THE DEFENSE: DEEP, MEDIUM, SHORT.  BECAUSE I AM STILL COACHING AT A YOUNG LEVEL, I TELL MY QB TO WORK FROM SHORT, TO MEDIUM, TO DEEP.  IF THE SHORT GUY ISN'T OPEN, LOOK MEDIUM.  IF MEDIUM ISN'T OPEN, LOOK TO DEEP.  IF DEEP ISN'T OPEN, RUN OR THROW IT TO YOUR MOTHER IN THE STANDS.  THE OLDER YOU GET, THE EASIER IT BECOMES TO WORK FROM DEEP ON DOWN.  I GOT THE CHANCE TO LISTEN TO RON TURNER OF ILLINOIS SPEAK AT A CLINIC, AND HE THROWS SHORT TO DEEP ALL THE TIME.
          THE ANSWER TO YOUR NEXT QUESTION IS A LITTLE MORE COMPLEX.  QB'S WOULD LIKE TO GET A PRE-SNAP READ. IF THE LINEBACKER LINES STRAIGHT OVER THE RECEIVER IN THE SLOT FOR EXAMPLE AND HIS EYES ARE LOCKED ON HIM, IT IS MAN AND HE RUNS WITH HIM.  IF IT IS ZONE THEN HE LINES UP ON THE INSIDE HIP OF THE RECEIVER, AND DROPS FAST INTO THE HOOK/CURL ZONE OF FLATS.  
          I AM RUNNING OUT OF ROOM, BUT IF YOU WOULD LIKE ME TO EXPLAIN WHAT BASIC COVERAGES THERE ARE, AND HOW TO READ THEM, PLEASE WRITE ME BACK AND LET ME KNOW....HOPE THIS HELPS........BRIAN