Black hole solutions refer to mathematical models that describe the properties and behavior of black holes in the framework of general relativity. These solutions help scientists understand how black holes form, their structure, and their effects on surrounding matter and light. The most famous black hole solution is the Schwarzschild solution, which describes a non-rotating black hole. Another important solution is the Kerr solution, which describes rotating black holes. These solutions reveal that black holes can have different characteristics, such as mass, charge, and angular momentum, influencing their gravitational pull and the way they interact with nearby objects in the universe.