The public float or simply the "float" of a public company is the number of outstanding shares in the hands of public investors as opposed to company officers, directors, or controlling-interest investors. These are the shares that are available for trading.
Additional meaning of Public float:
The float is calculated by subtracting restricted shares from outstanding shares. For example, a company may have ten million outstanding shares, but only seven million are trading on the stock market. Therefore, this company's float would be seven million. Stocks with smaller floats tend to be more volatile than those with larger floats. Large holdings of founding shareholders, corporate cross-holdings and holdings of the Government in partially privatized companies are usually excluded while computing the public float.