How to explain gaps in your resume
The situation is this--your resume gives plenty of details about all the jobs you have had so far, and the years you spent at school and college, but it is not complete. It has gaps in it of unexplained time--maybe there is a year missing between leaving college and starting your first job, perhaps there are months or even years between each job, or at least between some of them.
This is not good news if you are an employer who is looking at your resume and considering you for a job. Gaps worry an employer, because he does not know what they mean. They could mean that you were in prison during that time, or that you were fired from a job for incompetence and found it extremely difficult to get another. Either way, those gaps lessen your chances of success in the jobs market.
Or there could be explanations that are far less damaging to your reputation. For example, you took a gap year to travel to Thailand and Singapore. Or you were let go rather than fired, due to an industry downturn that affected many more people than just yourself. Or you stopped work for a while to look after an elderly relative in their last illness.
Don't be embarrassed by your past
The point is that, just from looking at your resume, the impending employer has no idea whether those gaps are for good reasons or bad. Unless you get to the interview stage you will have no chance of putting him right, and the gaps make that chance a remote one.
Taking time out from the employment rat race is not a bad thing, and not a cause for embarrassment. If it took you a year to find a new post, say so, but also say what you were doing during that time when you weren't filling in application forms and knocking on office doors. Perhaps you helped out at a community centre one evening a week, for example?
There's nothing wrong in accentuating the positive and eliminating the negative. "Studying the marine environment of the Northern Pacific" sounds a lot more worthy than "beach bumming and surfing in Hawaii"!
OK--let's suppose there really is something there that you'd rather forget about and would like to keep quiet, such as a spell in jail. The blunt fact is that it happened, you can't hide from it, and the fact doesn't help your job prospects.
If you leave it out, the employer will guess the truth or find out from other sources. This just adds deceitfulness to your record of misdemeanours, which hardly helps. However, you are presumably a reformed character and you need to emphasise this. If your offence was a minor one, such as a default on a fine, make this clear. Did you do community work as part of your sentence, or do excellent work in the prison library or kitchens? Again, make use of these high spots.
Remember that not everyone is a paragon of virtue and employers know this. The "perfect" resume is far more likely to excite suspicion than one that is honest. You don't have to do yourself down when writing the resume, but you must never tell a downright lie, and you must never leave gaps.