chord progression

[nhlt]

i have progressions that i wonder about the chords

1st . is --- C - D7 - F ----- CHORUS Em-Am-Dm all through the song

i know its in the key of C but how does the D7 chord fit in not being part of the key ?

2nd song, verse- Bm - F# - A - E - G - D - Em - F# - Bm - F# - A - E - G - D

chorus - G - D - Em - Bm7 - G - Em - F#


this would be key of Bm but how would the E maj chord be there sense its a min chord in the key of Bm


i know the F# would be from the B harmonic min scale .

[ageofaudio]

well, it's very common to use chords outside the main key.

D7 could be used as a chord in the key of C Lydian

the second song is a progression of II V, so basically it's not one key.

[tapper mike]

Any minor 7th can be subsituted with a dominant 7th. It's been a popular subsitution technique since the 1920's

And a song can have more then one key.