A sewing machine needle consists of:

• shank - clamped by the sewing machine's needle holder
• shoulder - where the thick shank tapers down to the shaft
• shaft - a length suitable for driving the eye and thread through the material and down to the bobbin
• groove - cut in the back of the shaft to release the thread into a loop that aids the hook or shuttle
  Bobbin drivers
  Throughout history, lockstitch sewing machines have used a variety of methods to drive their bobbins so as to create the lockstitch.-"Rotating shuttle":...
  
  to pick up the thread
• scarf - provides extra room for the hook or shuttle to pass close by
• eye - carries the thread
• point - penetrates the material by parting the threads or cutting a hole

Point types

Sewing machine needles each have one of three different point types:

• regular point, the finest point, for parting the threads of woven fabrics
• ball point, for knit fabrics; its round point minimizes cut threads by allowing them to move out of the way
• chisel point, for leather, capable of punching its own holes as it goes

Singer color codes

Singer colors its needles with a system of color codes which indicate the needle's type:

Shank color	Point type
red	regular, for woven
yellow	ball, for knits
blue	heavy-duty, for denim
brown	chisel, for leather

Shoulder color	Shaft size
green	9 (thinnest)
orange	11
blue	14
purple	16 (thickest)

Kenmore color codes

Kenmore colors its needles with a different system of color codes which indicate the needle's size:

Shank color	Shaft size	Shaft size (europe)
blue	11	75
orange	12	80
red	14	90
purple	16	100
green	18	110

Schmetz Color Codes

The colored band on some types of Schmetz needles indicates the needle type.

Shank color	Type
yellow	Stretch
blue	Jeans
green	Quilting
red	Embroidery
purple	Microtex (sharp)