There is little understanding of how people describe software problems, but a variety of tools solicit, manage, and analyze these descriptions in order to streamline software development. To inform the design of these tools and generate ideas for new ones, an study of nearly 200,000 bug report titles was performed. The titles of the reports generally described a software entity or behavior, its inadequacy, and an execution context, suggesting new designs for more structured report forms. About 95% of noun phrases referred to visible software entities, physical devices, or user actions, suggesting the feasibility of allowing users to select these entities in debuggers and other tools. Also, the structure of the titles exhibited sufficient regularity to parse with an accuracy of 89%, enabling a number of new automated analyses. These findings and others have many implications for tool design and software engineering