The resistor ...

R1 and R2 are connected in series and are connected in parallel to R3.
A voltage divider.

Typical resistor symbols and parts

IEEE symbol IEC symbol Photograph
 
resistor
 
resistor
 
through hole resistor
 
SMT resistor
 
potentiometer
 
potentiometer
 
potentiometer
 
faders
 
variable
 
preset
 
trimmer
 
multi-turn trimmer

External links