Introduction: The purpose of this study is to compare characteristics and features of user supplied tags and search query terms for images on the "Flickr" Website in terms of categories of pictorial meanings and level of term specificity. Method: This study focuses on comparisons between tags and search queries using Shatford's categorization schemes and the level of specificity based on the basic level theory. Analysis: Frequency distributions and chi-squared analyses were performed on the data. The results of statistical analyses demonstrated that there were significant differences in categories among tags and different stages of search query terms. The overall distributions of the levels of term specificity also had similar pattern in both tags and search query terms, but statistically significant differences were found between tags and search query terms. Results: The results of this study demonstrated that "Flickr" tags have their own unique features compared to users' queries for image searching. The findings suggest that image tags should not be generally applied to other image collections although they have been considered as useful data in developing a user-centered indexing system. Conclusions: When utilizing user-supplied tags for user-centered indexing systems, it is desirable to consider the functions and users' tasks applied in tags rather than depending on statistical features merely obtained from the tag analysis. (Contains 9 tables and 6 figures.)