Wat is Authorised participant, creation unit, creation basket?

An authorised participant (AP) is a broker-dealer that has contracted with an ETF for the right to create and redeem its shares. It does so in creation units, blocks of a fixed number of ETF shares, by delivering to the fund (or receiving from it) the creation basket: the list of securities and cash, published daily by the fund, that one creation unit is exchanged for.