What is the investment strategy called dollar cost averaging

I have talked repeatedly about the need to save regularly. To that I would add, "invest regularly as well."

My recommendation? If possible, make regular deposits from your monthly employment income into your investments. If you always invest the same dollar amount—say $100 a month—you are using a strategy known as as "dollar cost averaging." The technique of moving money into investments on a regular basis has been proven to mitigate the effects of short-term volatility. Sometimes you buy high, and sometimes you buy low, but overall you achieve an average purchase price for the investment over time.

It's easy to see why that's true. If you invest $100 every month in stocks, or a stock mutual fund, you will buy more shares when prices are down, and that will balance the fewer number of shares you will be able to buy when prices are up.