The article introduces Circos, a visualization tool designed to facilitate the identification and analysis of similarities and differences in genomic data. Circos uses a circular ideogram layout to display relationships between genomic intervals, making it effective for visualizing variation in genome structure and other positional relationships. The tool supports various data types, including scatter plots, line plots, histograms, heat maps, tiles, connectors, and text. Circos is flexible and can be easily integrated into data analysis pipelines through automated configuration files. The authors demonstrate Circos's capabilities by applying it to whole-genome structural data from follicular lymphoma patients, demonstrating its effectiveness in visualizing complex genomic rearrangements and identifying breakpoints. Circos has been widely used in genomics research and has been applied to generate images for various purposes, including book and magazine covers. The core strengths of Circos are its ability to illustrate relationships between genomic positions and its flexibility in rearranging elements within the image. The article also highlights the use of run-time rules to control the visibility and format of data elements, enhancing the visualization of sparse or non-uniformly distributed data.The article introduces Circos, a visualization tool designed to facilitate the identification and analysis of similarities and differences in genomic data. Circos uses a circular ideogram layout to display relationships between genomic intervals, making it effective for visualizing variation in genome structure and other positional relationships. The tool supports various data types, including scatter plots, line plots, histograms, heat maps, tiles, connectors, and text. Circos is flexible and can be easily integrated into data analysis pipelines through automated configuration files. The authors demonstrate Circos's capabilities by applying it to whole-genome structural data from follicular lymphoma patients, demonstrating its effectiveness in visualizing complex genomic rearrangements and identifying breakpoints. Circos has been widely used in genomics research and has been applied to generate images for various purposes, including book and magazine covers. The core strengths of Circos are its ability to illustrate relationships between genomic positions and its flexibility in rearranging elements within the image. The article also highlights the use of run-time rules to control the visibility and format of data elements, enhancing the visualization of sparse or non-uniformly distributed data.