COLOMBOS stands for 'COLlection Of Microarrays for Bacterial OrganismS'. It is a web based interface for exploring and analyzing comprehensive organism-specific cross-platform expression compendia of bacterial organisms. Colombos' major features include: 1. Access to expression compendia that combine information from different platforms and experiments (constructed by collecting, homogenizing and formally annotating publicly available microarrays from Gene Expression Omnibus (GEO), and ArrayExpress). 2.