In helping to create middle earth, John Ronald Reuel Tolkien created many things including races, lands, architecture, and languages. All of this is shown in his writings which include The Hobbit, The Lord of the Rings trilogy, and The Silmarillion. The most interesting thing about what he did was how complex his languages were.
One must have an extensive knowledge of language and grammar to create their own languages and Tolkien most certainly did. His mother introduced him to Latin, French, and German. While at school he was taught or taught himself Greek, Middle English, Old English (also called Anglo-Saxon), Old Norse (also called Old Icelandic), Gothic, modern and medievil Welsh, Finish, Spanish, and Italian. He (Noel 3). Perhaps the critical influence that directed Tolkien's creative genius towards the works for which he is best known occurred when, at the age of twenty-one, he read the Old English religious poem Crist by Cynewulf (Noel 4).
He did not, after all, 'invent' new words and names arbitrarily: in principle, he devised from within the historical structure, proceeding from the 'bases' or primitive stems, adding suffix or prefix or forming compounds, deciding (or, as he would have said, 'finding out') when the word came into the language, following it through the regular changes in form that it would thus have undergone, and observing the possibilities of formal or semantic influence from other words in the course of its history (Helge). All of the different races in middle earth had their own language which he created. Some of the languages are more complex than others. The most complex language that he created was Quenya, the language of the elves. He not only created the languages, he also created letters for the languages to give it an even greater mythical feeling. Below are some of the letters he created for his languages (Noel 48 - 49).
All of the languages are also tied together which is shown in the picture below (Noel, 54).