A triplet is a group of three evenly spaced notes played within one beat. Eighth note triplets are indicated by three eighth notes grouped together by a bracket (or a curved line) and the numeral 3.
The eighth note triplets are played with one third of a beat each. Triplets are easy to understand once you have heard them played.
Triplets sound great when combined with the notes of the Blues scale as shown in the following example.