To conlang means to construct a language. A person who creates constructed languages (conlangs) is a conlanger. Well-known conlangers (or conlangs) are, for example, J. R. R. Tolkien (Quenya from Lord of the Rings), Marc Okrand (Klingon from Star Trek), Paul Frommer (Na’vi from Avatar), or David Peterson (Dothraki from Game of Thrones). All of these conlangers are/were also linguists, so they studied natural languages (natlangs) spoken by humans on Earth, and used their knowledge to create naturalistic conlangs. It is not required to be a linguist in order to become a conlanger, but many devoted conlangers eventually become linguists (in the sense that they have extensive linguistic knowledge).

There are three commonly distinguished types of conlangs with different purposes: Artistic conlangs (artlangs), which are created just for the fun of it; they only serve to please their creator or an audience. All of the initially mentioned examples are artlangs, as they were all constructed either because their creators simply enjoyed conlanging and/or for a book or movie audience to enjoy. Many artistic languages also strive to be naturalistic, i.e. to mimic the beauty and quirks of natural languages. All of my own conlangs are naturalistic artlangs. Then there are auxiliary languages (auxlangs), which are supposed to facilitate communication, usually between speakers of different natural languages. A famous example is Esperanto (originally by L. L. Zamenhof), which was invented to be an easy-to-learn international language. Finally, there are engineered languages (engelangs), which are created to explore novel ways in which languages might work. An example would be Toki Pona (by Sonja Lang), which is fully expressive with only 137 words.