Tolkien’s true passion was not writing, but languages. From an early age he started creating his own languages that Tolkien enthusiasts are still learning to this day. As a teenager he and some of his friends created the languages Animalic and Nevbosh. Ever since then the young Tolkien became obsessed with creating languages.
The childish languages of Animalic and Nevbosh could hardly be called languages because consisted mostly of English code words and distorted words in English, German and Latin. Tolkien soon went on to create his own much more complicated languages. He didn’t just ascribe words to certain things; he constructed realistic and complicated syntaxes, suffixes, prefixes and roots. (For example “mor” means black and “dor” means land, so “Mordor” means “black land”.) Tolkien used real languages as a basis for his languages. His two most developed languages, Quenya and Sindarin, are based heavily on Finnish and Welsh. He invented these languages purely for his own enjoyment and intellectual stimulation, never dreaming that this hobby would become the basis for his stories about Middle earth. Tolkien realized that in order to create a language, one must have a culture surrounding it. LotR, the Hobbit, and all of his other writings were birthed from his invented languages. In a letter he wrote "The invention of languages is the foundation. The stories were made rather to provide a world for the languages than the reverse. To me a name comes first and the story follows... [LotR] is to me...largely an essay in 'linguistic aesthetic', as I sometimes say to people who ask me 'what is it all about?' "In another letter he wrote "Nobody believes me when I say that my long book is an attempt to create a world in which a form of language agreeable to my personal aesthetic might seem real, but it is true."
I am no expert in Tolkien’s Elvish languages, but you can find out more about them at this detailed site: http://folk.uib.no/hnohf/