An annotated bibliography provides a list of citations with descriptive and evaluative information about each item you cite. Annotations generally run 100-150 words. Professors dictate the annotation content, which could be to summarize content, evaluate the scholarship, comment on the usefulness to your research, or all three. Purdue University’s Online Writing Lab (OWL) provides detailed examples for annotated bibliographies in APA, Chicago and MLA styles (use the menu on the left to move through the 3 sections about annotated bibliographies). OWL is also a terrific resource for citation style help for all types of sources.