GPIO: General pupose input/output
in PIC 12F683 they uses GPIO for PIN denomination
in PIC 12F1840 they use RA0 RA1 RA2... RB0.. RC0... etc .. for PIN denomination
same as other PIC 16Fxxx 18F xxx familly
A MCU pin can be configured for
an input, or an output, or an analog input, or PWM output, or timer input..
etc .. depend of Harware configuration by your software.