Bunker oil is a dense, heavy fuel oil used primarily as fuel in ship engines. It is obtained through oil refining and comes in various grades defined by viscosity and sulfur content. Key regulations like IMO 2020 limit the sulfur in bunker oil to reduce pollution. While it provides energy, bunker oil also has environmental impacts like greenhouse gas and air pollutant emissions. Due to its properties, bunker oil requires specialized storage, heating, and handling onboard ships. The price fluctuates based on oil markets and supply/demand factors. Recently, there has been a focus on cleaner alternative fuels and technologies to reduce bunker oil's environmental effects in the shipping industry.