An exocrine gland puts out (excretes) its product by a duct. The duct goes to some environment outside the gland, either inside the body or onto the surface of the body.
An endocrine gland is its counterpart. It secretes its essential product directly into the bloodstream or else by diffusion into its surrounding tissue. Its product often acts on cells near the release site.
Examples of exocrine organs and glands: