Mucous glands are specialized glands in the body that produce and secrete mucus, a thick, slippery substance. Mucus serves various functions, including lubricating surfaces, trapping pathogens, and protecting tissues from irritation. These glands are found in various locations, such as the respiratory tract, digestive system, and reproductive organs. There are two main types of mucous glands: unicellular and multicellular. Unicellular mucous glands consist of single cells, like goblet cells, which are scattered throughout epithelial tissues. Multicellular mucous glands, on the other hand, are composed of clusters of cells and can be found in structures like the salivary glands and nasal glands.