The gland is an organ made of many cells that produce one or more substances like hormones, and digestive juices.
There are 2 types of glands in the body endocrine glands and exocrine glands.
Endocrine glands like pituitary glands, thyroid glands, parathyroid glands, adrenal glands release substances directly into the bloodstream.
Exocrine glands like salivary glands, mammary glands, lacrimal glands, eccrine sweat glands, pancreas, liver release substances on the body surface through a duct.
Secretions of exocrine glands:
Salivary glands secrete saliva and digestive enzymes which help in digestion.
Mammary glands secrete breast milk.
Lacrimal glands secrete fluid to cleanse the eye surface.
Eccrine sweat glands secrete salty water i.e. sweat through perspiration.
Pancreas secrete pancreatic juices that help in digestion.
Liver secretes bile which contains salts and digestive substances.