UCLUST is an algorithm, a finite sequence of computer-implementable instructions, described by the engineer as having two simple clustering criteria.
UCLUST is an algorithm designed to cluster nucleotide or amino-acid sequences into clusters based on sequence similarity. In mathematics and computer science, an algorithm (/lrm/ (listen)) is a finite sequence of well-defined, computer-implementable instructions, typically to solve a class of problems or to perform a computation. The algorithm is described by the author as following two simple clustering criteria, in regard to the requested similarity threshold T. The first criterion states that any given cluster's centroid sequence will have a similarity smaller than T to any other clusters' centroid sequence. 
