Treble Crochet Increase (2/3tr inc)

Standard name:  Increasing

Standard abbreviation:  inc

UK examples:
2tr in next st
2tr in next dc/tr
inc in next st
tr inc in next

USA examples:
2dc in next st
2dc in next sc/dc
inc in next st
dc inc in next

Increases are made by working a multiple number of stitches into the same stitch or chain space.  The standard term for an increase of any kind is 'inc' but can find variations in inc instructions:-

Tutorial (2tr inc):

 1.   Make one treble crochet (UK tr/USA dc) into the place where you'd like the increase.  Then a second stitch is worked into the same place.
 2.  Wrap the yarn around your hook and insert the hook into the stitch (or chain space).
 3.  Wrap the yarn over the hook and pull through the stitch (or chain space).

 4.  Wrap the yarn over the hook and pull through 2 of the 3 loops already on the hook.
 5.  Wrap the yarn over the hook again and pull through the remaining 2 loops on the hook to complete the stitch.
 6.  The increase is now made, 2 stitches where there was 1 stitch.

Tutorial (3tr inc):

 1.  If a 3 stitch increase is required, simply repeat steps 2 to 5 to make the third tr (USA dc) in the same place.
2.  The increase has been made, where there was 1 stitch, there are now 3.

This can be repeated to make as many stitches as the pattern requires.