I'm trying to analyze a pop punk song that sounds pretty interesting.
The song starts on an E chord, with a very major sounding riff that, to my ear, immediately puts the song in the key of E major. But as soon as it gives your ear time to adapt to the key you've just identified, it hits you with a C chord that's outside the key. I love that sound and would like to learn the theory behind it so I can add it to my arsenal.
The progression for the intro is E C C#m A. I know that E = I, C#m = vi and A = IV, but I don't know how to notate the C chord in this context. Is it a #V? A bVI? A "flat submediant"? What do you call that chord? Can you reference any materials where I can learn more about it?