While the information retrieval techniques used by web search engines have improved substantially over the years, the search results have continued to be represented in a simple list-based format. Although this list-based representation makes it easy to evaluate a single document, it does not support the users in the broader tasks of manipulating the search results, comparing documents, or finding a set of relevant documents. HotMap provides a compact visual representation of web search results at two levels of detail, and supports the interactive exploration of web search results. User studies have shown that HotMap can result in fewer low-relevance documents being considered, and generates a higher level of confidence, ease of use, and satisfaction than a Google-like interface.