Backdoor progression
In jazz and jazz harmony, the chord progression from iv7 to VII7 to I has been nicknamed the backdoor progression or the backdoor ii-V, as described by jazz theorist and author Jerry Coker. This name derives from an assumption that the normal progression to the tonic, the ii-V-I turnaround is, by inference, the "front door", a metaphor suggesting that this is the main route to the tonic.
The VII7 chord, a pivot chord borrowed from the parallel minor of the current tonic major key, is a dominant seventh. Therefore, it can resolve to I; it is commonly preceded by IV going to iv, then VII7, then I. In C major the dominant would be G7:, sharing two common tones with B7:. The notes A and F serve as upper leading-tones back to G and E, respectively, rather than B and F serving as the lower and upper leading-tones to C and E in a conventional G7-C major cadence.
A backdoor IV-V is also possible, moving from VIM7 to VII7 to I. This is also commonly known as a "Mario Cadence".