Latin has a very interesting history in the western world. Also, it is important to define "dead language" because many classical enthusiasts (myself included) have from time to time boarded the truly delightful lingua Latina mortuus non est train. The technical definition of a dead language is one that no longer has any native speakers. Latin did not actually die in this regard. It simply morphed into regional dialects which we now call Romance languages: vulgar (common) Latin became French, Italian, Spanish, etc. Even with this in mind, Latin "proper" as I shall call it, still had a remarkably long life after the fall of the Roman Empire. Gregory of Tours, a man who lived about 100 years after the fall of the empire in the west, still wrote in Latin. Latin continued to be the official court language for the Byzantine Empire for at least another 100 years beyond this. In the 7th century, ecclesiastical Latin could still be understood. It was a bit like a modern reader reading Shakespeare. In the same way, priests began preaching in either vervacular Germanic languages or in "vulgar Latin" (which varied depending on the region). By the mid-7th century, proto-French began to emerge as a language. The first recorded document is the Oaths of Strasbourg, a treaty between Charlemagne's sons. This is really when Latin proper began to be viewed as a seperate language. Even then it still developed its own pronunciation (Carmina Burana, a medieval poetry cycle set to music by Carl Orff, though often sung using the Roman or ecclesiastical pronunciation, was originally written with the old Germanic Latin pronunciation in mind. Quoque would be pronounced "kvokve" and mihi would be pronounced michi (a gutteral ch), and its own orthography. Eventually, pronunciation was standardized by the church, requiring everyone to use the Roman pronunciation, which sounded a lot more like modern Italian. Latin was very much a lingua franca throughout the middle ages and the Renaissance as well. If two foreigners did not know eachother's language, Latin was what they spoke, provided they knew it. Erasmus, the Renaissance humanist, wrote a book on conversational Latin designed for foreign university students so that they could converse more easily with one another. Erasmus himself was a prolific letter writer (I think he fancied himself a latter-day Cicero) and wrote all his letters in Latin. Universities lectured in Latin throughout the Renaissance, and in some places this lasted beyond the Renaissance. Oxford and Cambridge both required passing both Latin and Greek exams as a condition for admittance into the 20th century. The Greek exam was phased out in the 1910s and then the Latin exam in the 1920s. Along with this, the Catholic church still used Latin liturgy until 1965, when it was decided at the second Vatican council to use the vernacular instead. Latin does continue to be the official language of the Catholic church, however. It is the official language of Vatican City, and Pope Francis, along with his predecessor made it easier for the Latin mass to be performed again. In addition, Pope Francis also tweets in Latin. Hope this answers your question!