Why does a person need a “get”?
If a person was married under Jewish law, that person cannot technically remarry under Jewish law without a get. Many Reform rabbis are willing to perform a wedding for a person who has previously only received a civil divorce from his or her former spouse, but it is necessary to get a get in the Orthodox and Conservative communities. Reform, Reconstructionist, and unaffiliated Jews may still feel they need a get in order to conform to the strictist interpretation of the law.
Many non-religious Jews choose to marry under a chuppah (wedding canopy), sign a ketubah (marriage contract), and have a Jewish wedding performed by a rabbi or cantor, yet remain unaware that in order to be able to remarry under Jewish law they need to obtain a halachic divorce under Jewish law. If you are a non-religious, unaffiliated, Reform, or Reconstructionist Jew who married in a Jewish wedding ceremony, you may wish to get a get so that you can remarry under Jewish law and have that marriage recognized by all streams of Judaism. However, if this is not important to you, you may decide you do not need to pursue a get.
Orthodox authorities hold that Jews who were married in civil ceremonies must also receive a get in order to be able to remarry under Jewish law. So if you were married under civil law, you may still want to get a get to conform with a strict interpretation of the law.