Yeast, what do we need to know??

[Begin2Brew]

Ok, 2013 is the year for me to learn everything I can about yeast and brewing. What do you think we, as homebrewers, need to know about our yeast?

Topics I have learned:
Proper pitching rates
Cell counting
Cell viability
Starter step up
Slanting
Plating
Fermentation temps

So what else do we really need to know about yeast and how it relates to brewing?

 

[BradleyBrew]

oxygen and its influence on yeast / fermentation

 

[kh54s10]

I learned that yeast in grain sugar water with hops makes beer!

Since I started 2 years ago I learned starters/pitch rates and freezing yeast. I have saved a good amount on yeast already.

 

[el_caro]

Topics I have learned:
Proper pitching rates
Cell counting
Cell viability
Starter step up
Slanting
Plating
Fermentation temps

So what else do we really need to know about yeast and how it relates to brewing?

Another thing of interest is what effect the different strains will have on the taste of your beer.
If you have a favourite recipe do not be afraid to try different strains from batch to batch to learn first hand the effect of the different yeast on the character of the beer.