Can anybody tell what exact Fedora is used for other than 'general' & 'desktop usage.

Is Solaris good?

I want a unix/linux OS that can teach me everything about linux and it must be the most compatible OS out there, because I'm going to buy some unix/linux books and I currently have Xubuntu 6.10 Edgy installed but I'm curious that the books I buy and the functions/commands in those books & the teachings would working with Xubuntu.

Thank you very much

(Sorry for my English, I can't write full sentenced and all clear writing)