Just as a Jewish marriage requires a ketubah (marriage contract), so too a Jewish divorce requires a get (bill of divorce). The ketubah is a contractual agreement in which the groom pronounces his responsibilities to his future wife, and the financial arrangements in case of divorce or his death. The get is a document releasing the wife from her contracted role as spouse, declaring that she can now freely remarry without violating the prohibition of adultery.
Legally (according to Jewish law), a get must be written by a scribe at the behest of the husband specifically for this couple, stating both their names/nicknames and location. The get must then be given into the hands of the wife. Both the signing of the get and the receiving of the get by the wife must be witnessed by two proper witnesses. A husband may appoint an emissary to deliver the get. The wife may do the same, but ultimately the wife must receive the get into her hands (it may not simply be left in the mailbox).
While the get is a document that a husband gives his wife at his own initiation, a woman may initiate a divorce under certain circumstances by asking a rabbinical court to order her husband to give her a get. A husband who refuses to give his wife a get (or a wife who refuses to receive her get) will often be faced with punitive actions (fines, communal shunning, and even, in some places, physical “encouragement”).
The procedures for the get are derived from Deuteronomy 24:1 – “When a man takes a wife, and marries her… and she will not find favor in his eyes … he will write her a bill of divorce and give it in her hand and send her out of his house.”