Loop Samples are a type of sound file that can be used in a variety of ways. Most notably, they're commonly used by DJs for blending transitions, mix transitions, and beatmatching. As their name suggests, loops samples tend to have accompanying "built-in" loops that can easily be triggered on cue.
Sikk sounds is currently one of the only places I've found where you can download high-quality Drum loops samples. Another option is at Looperman's website- they also offer high-quality loop files but it's worth noting their sample packs are a bit expensive to Sikk Sound’s.