What is "scalping" and how does it work?

Scalping stands for capturing small price movements for profitability, where the duration of trade is very short.

This is what investopedia says on scalping: http://www.investopedia.com/terms/s/scalping.asp

Scalping is trading without any emotions. You trade with profusely with small fixed gain and fixed stop. In the long run you count all your nominal gains and get your days targets.