What kind of stitch makes up t-shirt seams on commercial grade clothing? I recently decided to take up sewing, but the stitches I use to hold two pieces of fabric together (like the side seams of a shirt for example) is a simple lock stitch. My machine (like most I've seen) has several different styles of stitches but none of them even remotely compare to the stitching I find on commercial grade clothing.

What type of stitch is this? My simple sewing machine stitches are nowhere near as sturdy as the stitching I am used to seeing on clothing.

The best picture I could find online (without knowing what I'm searching for) can be seen in this picture. The stitch holding the sleeve onto the body of the shirt is much fancier than anything my sewing machine seems to offer.



Image from LoveLaughPin.com
The stitches that you typically see on commercial t-shirt seams are an overlock stitch, which typically requires a special type of sewing machine specifically for this purpose (e.g., a serger).