The origin of high energy emission has always been a key question in AGN physics.
The gamma-ray bright blazars constitute a unique laboratory to probe jet formation
and its relation to radio-to-gamma-ray variability. A combination of high-resolution
VLBI images associated with densely time sampled multi-frequency flux measurements
of the extreme BL Lac object S5 0716+714 over the past four years allow us to study
its broad-band variability, allowing us to probe the jet acceleration zone, with
emphasis on the location and size of the emitting regions and the evolution with time.
We study the characteristics of some prominent mm-/gamma-ray flares in the context of
(1) the shock-in-jet models, (2) broadband spectral modeling, (3) and jet kinematics,
to probe the location of the high energy emission region.
Here, I will present and discuss the main results of the study.