sales tax vs. use tax (California)

[Desert Rat Books]

I am just getting started, officially. What is the difference between sales tax (and who does it go to) and CA use tax? Does this mean that every book I sell in CA gets taxed twice, at 2 possibly different rates? What is the best software for easily managing taxes (free or relatively cheap).

Or does sales tax get added to every book I sell, and those used in CA gets that sales tax?

If someone wants to "talk" with me about this off-forum, please do! I just want to understand the law so I can follow it. Rhona k899