There are few things more fundamental and important to becoming a technically competent photographer than mastering the exposure triangle. If you are new to photography, this fantastic video tutorial will show you how the exposure triangle works and how to use it to take better control of your photos.
Coming to you from John Branch IV Photography, this excellent video tutorial will show you how to use the exposure triangle to take full control of your images. The exposure triangle, which consists of shutter speed, aperture, and ISO, is the key not only to making an image with a proper exposure, but for taking creative control over your photos as well. Auto modes have become quite advanced and can certainly get the exposure nearly right the majority of the time, but any number of combinations of the three parameters can make a decent exposure in most situations, and the camera does not know which combination would be best for whatever creative vision you have in mind, which is why it is so important to take manual control a lot of the time. Check out the video above for the full rundown.
And if you would like to learn more about how the exposure triangle works, check out this article.