British coinage - half a penny
Old-style British coinage had a language all its own. The shilling was a "bob", sixpence was a "tanner". This one was pronounced "hay-p'nee" or even "ape-knee", aka half penny.
As a unit of UK currency, it was no longer legal tender in the UK after 1st August 1969. This was quite a shame, given that it had been around in some form (as the junior cousin to the penny) since Viking times. Silver halfpennies were minted by King Alfred the Great from about 886 CE. They were fairly rare (it cost almost as much to produce as the penny), and most halfpennies came into being through what appears to us an act of vandalism, the cutting in half of a penny coin. In the same way, farthings (literally "quarterings") were made by cutting the larger coin further still.
By the early 12th century minting began again. Ha'penny coins were certainly struck from 1108 (possibly earlier) by Henry I, and they gradually became more popular, so that by 1672, Charles II had them produced in copper. They were still not exactly commonplace as they were still expensive to make, although in 1860 the coin was made in bronze, and later still, copperplated steel.
Under the Influence of LSD
Under the old LSD monetary system, there were 12 pennies in a shilling, and 20 shillings to a pound. This meant that a ha'penny was worth 1/480 of a pound - not a lot, but in the early 1960s it would buy you four Black Jacks sweets, quite a treat for a small boy!
The old halfpenny passed into history on Decimal Day - 15 February 1971, along with all the "shillings and pence" which made life so interesting for overseas visitors to the UK. It was replaced by a much smaller coin, and this modern half penny (of which there were now 200 to the £) was in use between 1970 and December 1984, when it was withdrawn due to the sheer cost of minting.
The ha'penny's best claim to fame nowadays is in the pub game shove ha'penny in which coins are propelled up a board to score points, and in the phrase "haven't got two ha'pennies to rub together", an expression denoting poverty.