A septum is a dividing wall or membrane that separates two cavities or spaces in an organism. In humans, the most well-known septum is the nasal septum, which divides the nasal cavity into two nostrils. Another important septum is the interventricular septum in the heart, which separates the left and right ventricles, ensuring that oxygen-rich and oxygen-poor blood do not mix. Septums can also be found in other organisms and structures. For example, in plants, a septum can refer to the partition within a fruit that separates seeds. In general, septums play a crucial role in maintaining the organization and function of various biological systems.