Here's a link which explains each of the crochet symbols. It also provides a video of each type of stitch. You'll note there is a difference in the appearance of the symbols for the US/Japan and Europe. Your symbol is an European symbol for the treble stitch. Hope this helps.
Here are a few more links which provide explanation of crochet symbols; but these do not provide a picture of the symbol you provided in your question.
According to the symbol you have given us, it is indeed a treble stitch. If it was displayed as a capital "T" with a diagonal line (going either way), then the symbol would be a dc. But, where you do not have a straight line, at the very top, and you have two horizontally straight lines, you definitely have a treble. All of the links everyone has provided will clarify this for you.
I know everyone else said treble (triple) crochet, but please read your pattern carefully, because this is the symbol for the double crochet (in US patterns).
Answers & Comments
Verified answer
Here's a link which explains each of the crochet symbols. It also provides a video of each type of stitch. You'll note there is a difference in the appearance of the symbols for the US/Japan and Europe. Your symbol is an European symbol for the treble stitch. Hope this helps.
http://www.hassdesign.com/StitchLegend/
Here are a few more links which provide explanation of crochet symbols; but these do not provide a picture of the symbol you provided in your question.
http://www.geocities.com/Heartland/Cottage/3606/tu... SYMBOLS
http://www.garnstudio.com/lang/en/skole/hekle_diag...
http://www.stitchdiva.com/custom.aspx?id=91
EDIT: Here's another link showing the various crochet symbols (like the one at hassdesign).
http://happyhandicraft.com/page4.html
According to the symbol you have given us, it is indeed a treble stitch. If it was displayed as a capital "T" with a diagonal line (going either way), then the symbol would be a dc. But, where you do not have a straight line, at the very top, and you have two horizontally straight lines, you definitely have a treble. All of the links everyone has provided will clarify this for you.
Treble Crochet
If you are using a crochet chart instead of a pattern it's a treble crochet symble.
I know everyone else said treble (triple) crochet, but please read your pattern carefully, because this is the symbol for the double crochet (in US patterns).
See the conversion chart at the site below.
an under-stitching?
lol i've only ever watched crochet sorry