Vast, life-changing—and yet largely invisible to the naked eye—the full scope of the endocrine system can be difficult to grasp. It helps to visualize its different components and how they all fit together: this interactive graphic will show you where the endocrine glands occur in the body, while this lesson from the Khan Academy gives a useful introduction to the system and its overall function.

If you want to search through the vast number of hormones and their unique effects, the website You and Your Hormones is a great resource. Equally fascinating is the complex and intricate system that hormones use to deliver their message to groups of target cells in the body’s tissues.

Here you can learn more about the body’s trillions of cell receptors, what they’re made of, and how they help deliver the message from the hormone to the cell. This source can help you understand more broadly how the cells, receptors, and hormones all work together to carry out changes in the body.

What about that familiar experience, puberty? This website gives a crash course on the many male and female reproductive hormones that underlie puberty, while this source shows how those hormones are linked to the visible changes in the body. However, not everyone experiences puberty the same way: you may also be interested to learn more about the different types of puberty people can experience.

While the endocrine system functions normally most of the time, sometimes it can cause problems. You and Your Hormones has information on varied endocrine conditions—such as gigantism, endometriosis, and diabetes—that can all result from endocrine imbalances.

There’s so much more to learn about the role of the endocrine system in our lives. Curious about the science of pimples? Take a look at this video. This one explains how hormones control periods. And these TED-Ed videos reveal the endocrine system’s role in everything from hunger to metabolism to blood sugar levels.