Ever wonder what the Exposure Triangle is? Well here's your answer:

Video by Some Stuff Explained

https://www.youtube.com/watch?v=1E4mIlcSYLk
Video by Wolfcrow

Here is a great series of videos from Adorama everything you could possible want to know about the Exposure Triangle is covered.

https://www.youtube.com/watch?v=J8gpm_QYRgI
Exposure Triangle in Practice.

Understanding Exposure Part 1: The Exposure Triangle

Understanding Exposure Part 2: The Exposure Triangle

Understanding Exposure Part 3: The Exposure Triangle

Understanding Exposure Part 4: Shutter Speed

Understanding Exposure Part 5: Aperture Values

Understanding Exposure Part 6: Auto ISO

Videos by Adorama.

Here is another great video on the Exposure Triangle from SLR Lounge:

Video by SLR Lounge

Video explaining the "three basics" of photography:

Video by Matthew Gore

Here is another article on this topic from fstoppers.

Exposure In Photography.
More photography resources.
More photography videos.