How is a horizontal stabilizer attached to the fuselage and works as a trimmable Horizontal Tail as well? I am trying to figure out how does the horizontal stab attached itself to the plane and moves up and down? Is the HS attached by the rear spar and to the fuselage?
Fighter aircraft usually have their tailplane connected to the fuselage with a single pivot joint, as visible in this F-15 drawing:



Passenger aircraft often have a horizontal tailplane which is a single part, and as such, the entire stabilizer is being trimmed by an actuator around a pivot, as can be seen in this 727 drawing. The actuating system is different on newer aircraft, but the idea is the same.