Nupedia articles will, we hope, be exemplary specimens of the languages in which they are written. In general, we desire Nupedia articles to exhibit the following qualities (among others): unimpeachable standard usage, grammar, punctuation, and spelling; clarity (i.e., being readily comprehensible by Nupedia's audience); the use of active voice and concrete language (with examples); a high degree of logical structure that is made plain to the reader; lack of bias; and a natural, lively, and even witty style. For English-language articles, it is worth perusing Strunk and White's Elements of Style as a general guide to style. Within the general constraints of good usage and style, we want to encourage writers to be as lively, and even as humorous--or at least good-natured--as reasonably formal writing permits. Encyclopedia articles do not have to be written in a boring style, and Nupedia articles shouldn't be.
It is worth emphasizing that, though there are, in principle, no space constraints, there are constraints on our readers' patience. Consequently, we wish to avoid rambling articles and prefer them to be (if you will) densely packed with information.