Rebalancing: Rebalancing is when you bring the weightings of your portfolio of assets back to the original asset allocation that contained your level of risk.  For example, if you have 80% stocks and 20% bonds and the stock market suddenly moves higher, you may find yourself with 90% stocks and 10% bonds!  The idea is that you would sell the additional 10% position of stocks that appreciated, to allocate back to purchasing bonds so that you maintain the original 80/20 ratio.