What is a message?
A message is a collection of letters arranged to form some meaning.
Well then what is a letter?
A letter is a specific series of lines to form what we see as a letter.
For the display it is convenient to view each letter as a block of HIGH and LOW signals.
Since the message will always be 6 blocks high but can be any number of blocks long, it makes sense to break up a message into some sequence of columns, then we can move through the columns without having to read through the whole message each time we wanted to show something. That way we can scroll
through a message by changing where we start displaying.