A combination saw blade is used for both ripping (cutting with the grain) and crosscutting (cutting across the grain).
Combination saws are designed for all-around use when acceptable rips and crosscuts must be made with one saw blade. The larger gullets allow for deeper cuts and efficient saw dust escape on rip cuts.
Their unique design makes them a popular choice for all-around use, providing acceptable rips and crosscuts with a single blade.
Popular Tools sells more combination saws than any other category simply because of its unique design.