When applying for a job you will often find that most employers will ask for at least one reference from a previous employer. Depending on what job you are applying for you may need to give more than one, this may be a personal reference and a work reference. Most universities and colleges now even ask for references from people that are applying to go on certain courses so they can get an idea of what your character is like and how well you work. These references may be able to be completed by a former tutor.
When choosing who you want to ask for a reference you may be limited and only be able to give one or two employers, but if you do have a choice make sure you pick someone recent but who is most likely to be able to give you a good reference. You may not be able to give your current employer as they may not be aware that you are applying for a new job. If you do want to give them as a reference then you need to ask that they are not contacted, unless you have been offered the position. Companies like to see references from people you have worked with in similar job roles to the one that you are applying for.
Personal references should be provided by someone that has known you for a while but ideally not family.