New Language Tutorial on ielanguages.com: Latin
Thanks to Brandon, Latin is now featured on ielanguages.com!
The Romance languages derived from Vulgar Latin, the major spoken language(s) of the Roman Empire. Classical Latin is what is taught at universities and written in books today since most of Vulgar Latin was never written down. The Appendix Probi is an interesting list from the 3rd/4th century CE that shows the changes between the two (and encourages people to use the Classical Latin words instead of the more common Vulgar counterparts.)
If you’re not interested in Latin for religious purposes and don’t ever plan to visit Vatican City, where it is the official language, you can still read plenty of Latin at the Latin Wikipedia, which does include 20th century topics.