Shekel (Plural - Shkalim) is an ancient weight and type of currency used in ancient times, most notably in Judea. Before the currency, the weight was between 9-17 grams. The earliest shkalim were silver or gold ingots with their weights stamped on them. During the feast of Belshazzar, in the book of Daniel, an angel wrote on the wall 'Mene mene tekel uparsin', tekel, meaning a shekel in Aramaic.
In the New Testament, Tyrian Shekels are hypothesized to be the infamous '30 pieces of silver' given by the Romans to Judas.
Since 1980, Shkalim (Or more officially "Shequel', NIS or Shequel Hadash) have been the National currency of Israel, with the reverse side showing a modern interpretation of the Yehud coins.