Photo-tagging web sites provide several ways to annotate photographs. In this paper, we study how people use and respond to three different annotation styles: single-word tags, multi-word tags, and comments. We find significant differences in how annotation styles influence the objectivity, descriptiveness, and interestingness of annotations. Although single-word and multi-word tags are not normally differentiated, users prefer multi-word tags for their combination of descriptiveness and succinctness. We also discover that producers and consumers assess annotation styles differently in terms of ease of use, support for different user goals, and amount of effort required, demonstrating that allowing multiple modes of annotation is generally beneficial, as is considering both tag production and consumption.