Samplers are like computers in many ways. Most importantly, they have the ability to digitally capture sound and reproduce it. Most samplers are used in conjunction with MIDI instruments.
Samplers have many other features.
Digital samplers are most commonly used by musicians to recreate sounds of instruments or create sound effects to enhance the sound of their music. Other band create entire compositions using samplers. Samplers are also commonly used in the theatre for recreating sounds for live action plays or shows. The most simple of which is simply recreating a sound, whether it be a voice or music Samplers offer the ability to filter sounds, changing the basic sound into something different. Crossfading is another feature.