The basic objects in Noos are terms that can be distinguished in four categories: feature terms, strings, numbers, and symbols. All the terms are also values of Noos--i. e. there is no type/value class/instance distinction. We will not say much about strings, numbers, and symbols--in the current implementation of Noos they are just like Lisp strings, numbers, and symbols. However, this should not be conceived as the capability of using Lisp functions dealing with strings, numbers, and symbols. This is not the case, basic arithmetic operations, for instance, are provided by Noos. Information about strings, numbers, and symbols can be found on Appendix A. The next section introduces descriptions, the basic object in Noos, that later is expanded in Chapter 3. The notions and terminology conspicuous to Noos will be introduced gently in this chapter but they all can be found in the Glossary (Appendix B, page ).