The 'gRbase' package provides graphical modelling features used by e.g. the packages 'gRain', 'gRim' and 'gRc'. 'gRbase' contains data sets relevant for use in connection with graphical models (in particular all data sets used in the book Graphical Models with R (2012)). 'gRbase' implements graph algorithms including (i) maximum cardinality search (for marked and unmarked graphs). (ii) moralize. (iii) triangulate. (iv) junction tree. 'gRbase' facilitates array operations, 'gRbase' implements functions for testing for conditional independence. 'gRbase' illustrates how hierarchical log-linear models may be implemented and describes concept of graphical meta data. These features, however, are not maintained anymore and remains in 'gRbase' only because there exists a paper describing these facilities: A Common Platform for Graphical Models in R: The 'gRbase' Package, Journal of Statistical Software, Vol 14, No 17, 2005. NOTICE 'gRbase' requires that the packages graph, 'Rgraphviz' and 'RBGL' are installed from 'bioconductor'; for installation instructions please refer to the web page given below.