  Magnetic twist of the active region has been measured over a decade using
photospheric vector field data, chromospheric H_alpha data, and coronal loop
data. The twist and tilt of the active regions have been measured at the
photospheric level with the vector magnetic field measurements. The active
region NOAA 10930 is a highly twisted emerging region. The same active region
produced several flares and has been extensively observed by Hinode. In this
paper, we will show the evolution of twist and tilt in this active region
leading up to the two X-class flares. We find that the twist initially
increases with time for a few days with a simultaneous decrease in the tilt
until before the X3.4 class flare on December 13, 2006. The total twist
acquired by the active region is larger than one complete winding before the
X3.4 class flare and it decreases in later part of observations. The injected
helicity into the corona is negative and it is in excess of 10^43 Mx^2 before
the flares.
