We need to have a clear goal in mind. 

What is expected of us?
What exactly does a circuit board designer create?
What is the end result we are trying to achieve?

So...  We are starting at the END.

Your goal as a circuit board designer
is to convert ideas into reality.

A schematic is a way to describe someone's idea by using symbols that anyone who knows electronics can understand. But it's still just an idea. The schematic must be converted into something that you can hold in your hand, a physical 'something' that hopefully functions the way the creator of the idea (let's just call him The Engineer) thought it would.

You will take the schematic from The Engineer and convert it into something that can be manufactured and tested. What the manufacturing and test people need from you is DATA, which can be broken down into two major categories:

• data used to manufacture the bare-board 
• data used for the board assembly and test

(NOTE: You will likely be asked for various pieces of data along the way, such as component lists for the purchaser to start planning buys with, or preliminary drawings for quoting purposes, schedule information for project managers, maybe data for simulations; but at the end of the job you will have created two major packages of data, one for fabricating bare boards and one for assembly.) 

Let's take a brief look at each type

BARE BOARD FABRICATION DATA
Let's hope that by the time you are reading this, the industry will have adopted a common data format for board manufacturing, all software will be able to output it in a single file that any vendor can use, and you won't have to know too much about this stuff. But at the time of this writing that is NOT the case. Some are working towards that goal, and have introduced newer formats such as GenCAM or ODB+, but in the meantime you need at least an overview, so here goes:

Wait...       STOP !!! 

I have a better idea. The descriptions of the data formats will make more sense if you have some idea how a circuit board is made.
The next screen will present a short tutorial, as brief and concise as I can make it.

Don't panic, this will be fun!

Go ahead, click to the next screen....

We can talk about this data stuff afterwards, ok?