The endocrine system is a series of glands that are spread throughout the body. These glands secrete regulatory chemicals called hormones or chemical messengers that control bodily functions. So, in short, the endocrine system is a collection of glands that control the various functions of the human body by secreting hormones. Hormone is the main regulatory unit for several bodily functions like metabolism, growth and development, tissue function, reproduction, sleep, etc.
A gland is an organ that produces hormones. Glands are of two types: exocrine and endocrine. The exocrine gland secretes components through a duct directly on the site of need. For example: salivary gland and sweat gland. Endocrine glands secrete components into the bloodstream through which these chemical components are transported to the site of need (other parts of the body away from the location of the gland).
