Explain the managed floating exchange rate system that China introduced in July 2005. Why was it introduced?

Question:

Explain the managed floating system that China introduced in July 2005. Why was it introduced?
Exchange Rate
The value of one currency for the purpose of conversion to another. Exchange Rate means on any day, for purposes of determining the Dollar Equivalent of any currency other than Dollars, the rate at which such currency may be exchanged into Dollars...