In humans a pair (two in number) lungs are found in the thoracic cavity. It is a soft color and pink organ of pink. Lungs are very soft and vital components, so for their safety there is a strong cover of the ribs around them. A thin cover is found around every lung called the Pleura. It is made of double membrane, and in it the thick sticky fluid is filled with pleural fluid. Due to this fluid, there is no rubbing in the lungs even after lung functioning.