Even though it makes headlines when celebrities get an annulment of their marriages based on fraud or inability to perform, annulments are relatively rare.
Fraud is usually the basis for an annulment. Examples are failure to disclose a previous marriage, criminal record, infectious disease, the inability to have children, or the desire not to have children. Annulments have also been granted where a spouse mistakenly believes they have been divorced or widowed when in fact they are not, or the spouses are too closely related, or one party is underage, and did not obtain appropriate parental consent.
In Maryland, a marriage which qualifies as one suitable for annulment means there is some legal defect that invalidates the marriage such as a spouse that is married to someone else at the time of the second marriage or the parties are blood relatives or one is underage. You do not need to file a petition for an annulment with the court in the case of a void marriage although it may be wise to do so anyway so that you have a court order of annulment.
A voidable marriage, on the other hand, can only be annulled by filing a petition for annulment with the court and having a judge declare the marriage not to have happened. Examples of voidable marriages are sham marriages or joke marriages where the parties did not really intend to marry. You can also ask the court for an annulment if you or your spouse were incapacitated at the time of marriage, as in insanity, intoxication, fraud or duress. Fraud can be hard to prove to a judge especially when the annulment is contested, so most people opt for a divorce instead. A divorce says the marriage is over. An annulment says it never happened.