Amalek is a term with several related meanings.
The word and derived words occurs in the Hebrew Bible and refer to a grandson of Esau, his descendants (Amalekites), and the territory of the Amalekites. As a people, the Amalekites were identified as a recurrent enemy of the Israelites.
In Judaism, the Amalekites came to represent an archetypal enemy of the Jews. In Jewish folklore the Amalekites are considered to be a symbol of evil.
During the Purim festival, the Book of Esther is read in the commemoration of the saving of the Jewish people from Haman (considered to be an Amalekite) who leads a plot to kill the Jews. On the basis of Exodus 17:14, where the Lord promised to "blot out the name" of Amalek, it is customary for the audience to make noise and shout whenever "Haman" is mentioned, in order to desecrate his name. The story also includes the claimed killing of 75,000 of the Jewish peoples' enemies.
Of the 613 mitzvot (commandments) followed by Orthodox Jews, three refer to the Amalek. They command that what the Amalekites did to the Israelites shall not be forgotten and that the Amalekites shall be exterminated.
Some Jews in post-biblical times have sometimes associated contemporary enemies with Haman or Amalekites and some Jews have been argued to believe that pre-emptive violence is acceptable against such enemies.
Various disliked groups/countries have been identified as Amalek, including atheists, disliked Jewish groups, Palestinians, Arabs, and Iran. This has been argued to increase the risk of violence and war against such groups/countries.
Baruch Goldstein, an Orthodox Jew, in 1994 killed 29 Muslims just before the holiday of Purim, which has been suggested to be related to seeing Palestinians as Amalek. Some Orthodox Jews/Jewish settlers have praised Goldstein and his tomb even became a site of veneration before it was dismantled by the Israeli army after the passing of Israeli legislation outlawing monuments to terrorists.