The Kaddish is an ancient Aramaic prayer used in various ways during prayer and is found in the Jewish prayer book - the Siddur. There are two forms of the Kaddish a shorter "mourner's" prayer and a slightly longer "reader's" prayer. There is also a "half" Kaddish, which is the first half of the reader's Kaddish. The reader's kaddish separates parts of the morning, afternoon, and evening prayers, while the half Kaddish separates smaller divisions within one part.
In addition to these uses, Kaddish is prayed by the men of the family (and other than the family) of the deceased loved one at the time of decease and at the yearly anniversary remembrance (Jahrzeit). Though it is a prayer for the departed, there is no mention of death. It is rather a prayer for the glorification of God who is the righteous judge.
May His great Name be Magnified and Sanctified in the world which He has made according to His will. And May He cause His Kingdom to reign in your lives and in your days and in the lives of all the House of Israel speedily and soon - and say Amen!
Reader and Congregation -
May His great Name be blessed forever and ever.
(Half Kaddish ends here)
Exalted and praised and honored and exalted and lifted up and adored and magnified and extolled be the Name of the Holy One, Blessed be He, whose Glory transcends, yea, is beyond all praises, hymns, and blessings that man can render unto Him in the world - and say Amen!
said only in the longer version -
(May the prayers and the supplications of the whole house of Israel be acceptable unto their Father in heaven - and say Amen!)
May there be abundant peace from heaven and life for us and for all Israel - and say Amen!
(said in Hebrew) May He who establishes peace in the heavens, grant peace unto us and unto all Israel - and say Amen!