In dollar-cost averaging, instead of buying all their capital at once, an investor puts a defined amount of money into the market at fixed intervals (say, weekly or monthly). The result is that more of the asset gets bought at lower prices and less at higher prices.
This method suits people in particular who don't want to worry about timing their market entry precisely and prefer to spread the risk of price volatility over time, rather than tying the fate of their entire capital to a single buy decision.