The info line at the Israeli Flash90 image service where I obtained this picture reads: “A child stands near a wall decorated with masks at her school which is preparing for the holiday of Purim.”
I got the sneaking suspicion from the line above that it is the wall which is preparing for the holiday of Purim, rather than the lovely child or her school – but that’s OK, walls can celebrate, too.
But why is Purim associated with wearing makss, or, alternatively, sticking them on a wall? Ask Wikipedia!
The custom of masquerading in costume and the wearing of masks probably originated among the Italian Jews at the end of the 15th-century. [Kohler, Kaufmann; Malter, Henry, (2002). “Purim”. Jewish Encyclopedia.]
The concept was possibly influenced by the Roman carnival and spread across Europe. The practice was only introduced into Middle Eastern countries much later during the 19th-century. The first among Jewish codifiers to mention the custom was Mahari Minz (d. 1508 at Venice).[Responsa no. 17, quoted by Moses Isserles on Orach Chaim 696:8.]
While some authorities were concerned about the possible infringement of biblical law were men to don women’s apparel, the accepted consensus was to permit all masquerade, as it was viewed as a form of merry-making. Some rabbis went as far to allow the wearing of rabbinically-forbidden shatnez (but not Torah level shatnez, which is a mix of wool and linen).[Yitzchak Sender (2000). The Commentators’ Al Hanissim: Purim: Insights of the Sages on Purim and Chanukah.]
Other reasons given for the custom: It is a way of emulating God who “disguised” his presence behind the natural events described in the Purim story, and has remained concealed (yet ever-present) in Jewish history since the times of the destruction of the first Temple—the “hester panim,” God hiding His “face.” Mind you, God’s name is not mentioned in the Megillah, even though His hand is felt in every chapter, which is the Biblical expression of hester panim. God is wearing a mask, if you will.
And since charity is a central feature of the day, when givers and/or recipients disguise themselves this allows greater anonymity thus preserving the dignity of the recipient.