The talk was about a tool called "iBySigma" that allows for visual network analysis and graph visualization in Jupyter notebooks. The speaker discussed the history and importance of visual network analysis and showcased some examples using the tool, including visualizing a network of French open source communities and analyzing graphs of speakers and rooms at conferences. The tool provides various options for customizing the visual representation of graphs and supports interactive exploration and manipulation. The speaker also mentioned the integration of other tools like Pelot for additional graph analysis capabilities. The tool utilizes WebGL for rendering and can handle graphs of various sizes depending on the capabilities of the browser and hardware.