A: a job that ended so ignobly that you don't even want to acknowledge it existed
B: you spent a long time out of the game and weren't getting experience etc during that time
C: something prevented you from working/being a good candidate
A gap is not the death knell it used to be, especially one in the past. That said, it's still nice to offer a vague reason - homemaking or health problems or something. So long as it's clear you didn't spend 3 years selling drugs and playing video games an employer probably won't care.
A: a job that ended so ignobly that you don't even want to acknowledge it existed
B: you spent a long time out of the game and weren't getting experience etc during that time
C: something prevented you from working/being a good candidate
A gap is not the death knell it used to be, especially one in the past. That said, it's still nice to offer a vague reason - homemaking or health problems or something. So long as it's clear you didn't spend 3 years selling drugs and playing video games an employer probably won't care.