A Sex offender is an individual who has in one way or the other committed a crime that is of a sexual nature. There are many terms used to refer to such a person, including sex abuser, sexual offender, etc, depending on the area you live in.
Furthermore, there are differences in the crimes and actions that can be categorized as sex offences depending on the areas and countries that one lives in. For example, in certain places, even public urination can be considered a sexual offence. Moreover, although a majority of sexual offenders are convicted for crimes that are relevant for consideration as sex offences, some of the charges are simply pressed because a person violated certain laws that were in the sexual category.
For example, in many states owning or viewing child pornography is also considered a sexual offence, and the person is categorically considered a sex offender. His punishment or penalty may, of course, be different from someone who is convicted for rape or some other more severe kind of sexual offence.
The punishment that a sex offender may receive varies from state to state. However, it is interesting to note that many countries and states have now started therapeutic program for such offenders in order to reduce such behavior in them. Results of such therapies have been quite positive and surveys have revealed that a sex offender does decrease his sexually offensive behavior after he has gone through sufficient amount of therapy.