LACE WEIGHT - Used for lacey projects
knitting,crochet and tattering

SOCK WEIGHT - Fingering, sport worsted

Dk WEIGHT - (Double knitting yarn) ideal for quick 
knitting and crocheting

WORSTED WEIGHT - most familiar for making a large
variety of projects

SPORT WEIGHT - Used for lightweight projects

FINGERING WEIGHT - Great for shawls,baby items

BULKY WEIGHT & SUPER BULKY - Good for bulky
projects (sweaters)

Fiber Facts

Acrylic - Man made fiber called propylene is machine washable
and dribble
Alpaca  - Smooth and heavy, warmer than wool.  Alpacas are
related to the camel and llamas
Angora - Of the angora rabbit, soft, fluffy and warm

Cashmere - Is less fluffy but soft, smooth and warm comes from
the capra hircus (goat)
Mohair - Is from a goat called angora.  It is strong and light 
weight, it is very delicate and spun  usually  with 
wool, nylon
Silk - From the caterpillar called silkworm 

Wool - Is from the popular sheep and is know for its warmth
and strength.  There are different breeds  and texture of
wool
Cotton - A bush like plant.
Mercerized - is a treatment with  caustic soda solution that 
increases the lust of the cotton
Linen - is the product of the flax plant.  It is strong, slightly
stiff and has lust

Yarn Equivalent
2 strands Fingering = 1 strand sport weight
2 strands sport = 1 strand worsted weight
2 strands worsted = 1 strand bulky
 
 

Most manufacturers list yardage on their labels