The endocrine system is similar to the nervous system in that it transmits information from one part of the body to another. the difference is while the nervous system employs neurons, the endocrine system uses hormones to transmit the information.
All multicellular organisms produce hormones, we have over 50 pumping through our bodies right now. The reactions produced by these hormones can take longer than the transmission of information through the nervous system, but the responses last longer too.
The endocrine system regulates endocrine glands transmitting hormones inside the body, such as the pituitary, thyroid, and adrenal glands. It also regulates exocrine glands like the salivary glands, which transmit substances out from the body.
The endocrine system, like all others is perfectly designed to keep everything inside our bodies balanced.
From Crash Course: Biology on YouTube presented by Hank Green.