Buy and hold is a long-term investment strategy based on the view that in the long run financial markets give a good rate of return despite periods of volatility or decline. This viewpoint also holds that short-term market timing, i.e. the concept that one can enter the market on the lows and sell on the highs, does not work; attempting timing gives negative results, at least for small or unsophisticated investors, so it is better for them to simply buy and hold.
Additional meaning of Buy and Hold:
The antithesis of buy-and-hold is the concept of day trading, in which money can be made in the short term if an individual tries to short on the peaks, and buy on the lows with greater money coming with greater volatility.