The treble or triple crochet stitch (abbreviated as tr) is a little taller than a double crochet, and is slightly more advanced as well.
The triple crochet stitch is a taller stitch than the double (or single), and is used when a longer stitch is needed within a crochet pattern. One of the common qualities of the treble/triple stitch is that it makes for a very loose pattern in the areas it is used. The treble crochet stitch is often used when crocheting a front- or back-post stitch. This is typically used to create crochet cables, basket weave stitches, and other similar designs.
The triple crochet stitch is an easy crochet stitch to learn, and is one of the basic stitches every crocheter needs to master early on.
Free Crochet Patterns using the Triple Crochet Stitch
These free crochet patterns were all created using various yarn types, brands and hook sizes... but all use the Triple Crochet crochet stitch.