Provides the academic community with free and reliable web tools for Bioinformatics and Genome research. GEDA provides a gene expression data analysis tool. The GEDA tool calculates the averages of probes from different genes if the genes have the identical gene name. The sample classification module in the GEDA tool can be used in two modes for sample classification-class discovery (unsupervised clustering) and class prediction (semi-supervised). In the first mode, the user should set the threshold for any test low enough to allow all genes to pass the test. Then clustering of the samples will be performed using all genes in the data set.