See anova.glm for details. In brief, specifying a single object, results in the display of a sequentila analysis of deviance table for that model. Specifying several objects, a table indicating the results of the likelihood ratio tests between successive models is displayed. The models must be nested and fit to the same data set..
References
Ho, Y. H., Landy. M. S. and Maloney, L. T. (2008). Conjoint measurement of gloss and surface texture. Psychological Science, 19, 196--204.