Why do airport gates have letters after them such as gate 12 then theres gate 12b?

Question

i think i know why in the case of gate 12b becasue they may be superstitious about having a gate 13 but wat about all other gate numberings besides that. fresno has this two someone said its because they have two jetways on the same gate but thats not true does anyone have the answer

Answer 1

The designation "b" is used for ground level gates that corrispond to an upper level gate (or jetway). Four of the upper level gates in Fresno (gates 11, 12, 14, and 15) have both jetways and stairs that lead to lower level gates. Gate 11 would be the jetway, 11b would be the stairs that lead down to the tarmac (or "ramp"), and so on. These lower level gates are rarely used. If they are used, it is for one of the following two reasons: 1) A turborop is being boarded. Jetways are rarely compatable with turboprops, so ground level boarding must be used. However, there are already six gates in Fresno exclusively devoted to lower level boarding. 2) All the jetways are being used by other aircraft.

Answer 2

I've only seen that when, like you said, two planes can use the same gate to embark & debark passengers - one on the left & one on the right.