Explain what is meant by the terms auxin precursors

Explain what is meant by the terms auxin precursors, anti auxins, free auxins and bound auxins.

The compounds, which can be converted into auxins, are called auxin precursors. The compounds, which inhibit the actions of auxins, are termed anti-auxins. The auxins, which can easily be extracted, are called free auxins. And auxins, which are hard to extract and need the use of organic solvents, are referred to as bound auxins.