Marriage is a contract, and when a court judge dissolves that contract it is called a “divorce”. When that contract is ended, the two people that were in the marriage are then considered “single”. This is very different than an annulment which is a judgment by the court that says the marriage contract was never valid in the first place. You can not get a divorce in some countries and some religions, like the Catholic church, does not recognize divorce, only annuments.
Some of the things that the divorce law helps determine is who has custody of the children, how much child support, and to whom it should be paid and who gets what property. If there are any debts and assets those need to be split up too. An annulment does not have the same rights involved.
In some places in the world you have to claim your partner did something wrong in order to get a divorce, but most places have a “no fault” policy which allows divorce if there are substantial differences that can not be reconciled. The rate of marriages that end in divoce has increased sharply in the past 100 years of history. Many think that is because it has become more socially acceptable.
This is for informational purposes only, consult a lawyer if you want advice on marriage lw.