KEGG BRITE is a collection of hierarchical classification systems capturing functional hierarchies of various biological objects, especially those represented as KEGG objects. They are represented as BRITE hierarchy files, also called hierarchical text (htext) files, supplemented with BRITE table files using html tables. BRITE hierarchy files may contain tab-delimited attributes that are added manually or computationally. BRITE table files focus more on such multi-column attributes rather than hierarchy relationships. In contrast to KEGG PATHWAY, which is limited to molecular interactions and reactions, KEGG BRITE incorporates many different types of relationships including: KEGG BRITE is the reference database for brite mapping in KEGG Mapper.