Why do i always get shocked during the winter when i touch a light switch or doorknob?

Shock: In the dry weather, you can build up an electric charge called an electrostatic charge that is high enough in voltage to cause a spark when the body touches something that conducts electricity that is at a different voltage level, ie ground. The current level is very low making it harmless although it can set a flammable substance like gasoline on fire.

Static shock: In the winter, when the air is dry and conducts electricity poorly, and you walk with dry shoes, especially with rubber soles, across a wool rug, your body accumulates a charge that in moist air would spontaneously leave. Then when you touch a metal point which goes to ground, the charge you have accumulated jumps to the ground and you feel the static shock. This is harmless but gets your notice.