Call signs, like phone #'s, have a prefix and suffix. In the case of a FCC issued tech class call, it's broken down like this:
is the prefix
K= the U.S. west of the Mississippi. W=eastern U.S. A&N are also used for General and advanced/extra class. K,W,A & N are only used in the U.S.
C= The series, once all available letter combinations are used up in the suffix, the series changes A,B,C,D, etc..etc. (all the cool kids have or had a C series call, everyone else will have a D of E series
Ø= call district, zero land is ND,SD,MN,IA,MO,KS,NE & CO.
= the suffix
The tech suffix starts with AAA and runs to ZZZ there are a few combo's that are not allowed.
The suffix identifies the individual station.
*hint* remember this, you WILL be tested on it.