I thought I understood this. But, in my infinte dumbness, I have
discovered that i truly do not.

I am trying to gain a better understanding of the definition of
primary and secondary fermentation. Specifically, what defines the
seperation between the two. I have read some, and in the last year, i
have made 5 5-gallon batches. All of these were with different
recipes.
So, I understand the basics. Primary fermentation is open to the air,
and yeast converts sugar to alcohol. After some period of time, or
some measurement, the wine is racked off the lees into an airtight
container to continue for several weeks.
I am specifically leaving MLF out of this for right now.
I guess my question is this, what to most of you use as an indicator
for when to transfer wine wine from primary to secondary.

* A fixed period of time?
* A Specific gravity reading?
* A leveling out of the SG at a certain level?

What are we looking for here?

Sorry for the newbie question, but this has been bugging me for a bit
now.