Computational linguistics is a rapidly growing interdisciplinary area of research and technology. The scientific disciplines on which it draws most heavily are Computer Science (especially, Artificial Intelligence) and Linguistics.

Any technology that seeks to use computers to perform intelligent tasks that involve human language falls within the scope of computational linguistics. This includes speech technology (speech synthesis as well as speech interpretation) and technologies that deal with written language, including the interpretation and generation of texts, intelligent information retrieval and document synthesis, machine translation, intelligent human-computer interfaces, and many other applications.

There are many excellent locations where you can find out more about computational linguistics; see especially the general information prepared by the Association for Computational Linguisics and Hans Uszkoreit's explanation of what it is all about.