A lack of consistent employment without a reasonable explanation will look bad on your CV and your application could be instantly rejected. Send a covering letter with your CV and clarify why there is a gap in the history of your employment, as there could be a perfectly legitimate reason and you want to make this abundantly clear and leave no reason for doubt.
If there is no way of avoiding the gap in employment, trying to put in an explanation is generally preferable to ignoring it completely. Many employers will discard your CV at first glance if there are unexplained gaps because they will instinctively draw their own conclusions as to the reasons for the gap and their interpretation of the events may not necessarily be a positive one.
There are probably some gaps in employment that you need not bother mentioning and these particularly include those that were only for a couple of months at a time or those that occurred a very long time ago. On a CV, the easiest way to avoid these sorts of gaps being highlighted is to only give the years for your employment rather than the months. On the other hand, the gap in employment may well have been used constructively and you may consider that it will add value to your CV.
If the gap in your employment is because of time taken to travel, the decision whether or not to include it is dependent upon how long the career break was for and whether or not you did anything fulfilling during this time. Not all employers look on a career break for travelling as a disadvantage. On the contrary, many believe that the cultural awareness and sense of independence you will have gained as a result of the experience will prove invaluable to you in your future career. Perhaps you were able to undertake further qualifications or training during this time and, if so, these should be included in your CV.
Many people have gaps in their employment due to having taken maternity leave. Indeed, paternity leave is now also becoming commonplace and should probably be included in the CV, particularly if you have also undertaken any part-time work or studying during this time. It can also be useful to cover this subject in your cover letter by emphasising the fact that you have made all the necessary childcare arrangements and are now ready to return to the workplace.
Sometimes, no matter how hard you have been trying, the right job is just not out there for you and you have a gap in your employment history purely for this reason. It is often very difficult for this scenario to be given a positive slant as many employers will find it easier to believe that you have just been idle during this time. Again, the key is to highlight anything positive that you have undertaken during this time and, if you haven’t actually achieved anything, then perhaps you can try to find something that you can do that will add value to your CV. For example, even though you have not been able to find a suitable job, there may well be a voluntary position that you can take on just to keep you active during this time. Alternatively, you could complete additional qualifications or training programmes. Either way, when preparing your CV and cover letter, make sure that you clearly state how you have been proactive in your job seeking during this time and that you are readily available to start work at the convenience of the employer.
You should never be tempted to extend the length of time you were in employment to cover any of these gaps because an employer is more than likely going to take references from your previous employers and will be able to find out straight away whether or not you have been dishonest. Whatever the situation is, just be positive and make sure that you come across as enthusiastic and ready for work.