IV7 roman degree
The subdominant as a dominant — IV with a minor 7th, a bluesy colour that pulls toward I by the 'backdoor' or tonicises bVII.
Where it lives
5semitones from the tonic
Major mode
dominant 7th
Hear it in context: 12-Bar Blues Skeleton
Piano sound loads on first tap. Resolved in the key of C — every chord links to its full analysis.