Knitting Needles are usually available in three types: 
(1) Single Pointed Needles
(2) Double Pointed Needles
(3) Circular Needles
Needle thickness is designated by number. For example, a #0 needle is much finer or thinner than a #13. The smaller the number, the finer or closer knit are the stitches and the finer the yarn used. Generally thin yarns are worked on smaller number needles and thick yarns are worked on larger number needles. If a needle is too large for the yarn, the resulting knitted fabric will be loose and flimsy. If a needle is too small for the yarn, the resulting knitted fabric will be compact, rigid, and inelastic.  The recommended needle size is usually designated on a yarn label.
Needle length is chosen according to the project's dimensions and should be a comfortable length to hold all the stitches. In general, shorter needles are easier to manipulate.
Knitting needles are made of plastic, metal, or wood and the material chosen is usually governed by personal preference.
Knitting needles may also referred to as "knitting pins."

Single Pointed Knitting Needles

Single point knitting needles are straight, rigid needles used in pairs for knitting flat pieces. These needles are usually available in 10" or 14" lengths and in sizes #0 through jumbo sizes (#17 or larger). Aluminum, plastic, or bamboo are the common materials for these needles. 

Double Pointed Knitting Needles

Double point knitting needles come in sets of 4, 5, or 6 needles. These needles are used to knit small, round, seamless items such as socks or gloves. Double pointed needles are abbreviated "dp."

Circular Knitting Needles

Circular knitting needles are used to knit round, seamless sweaters or large flat projects that will not fit on a straight needle. The needle is made of two needle tips connected by a flexible (usually nylon) cord. Before the use of nylon, needles where connected by a metal cording. Aluminum, plastic (nylon), or bamboo are the common materials for these needles. 
When choosing a circular needle, select a length that is at least 2" shorter than the finished project length or circumference.

Tape Measure

A tape measure or measuring tape is a ribbon of cloth, plastic, or metal with linear-measure markings, often in both imperial and metric units. Tape measures are typically made of flexible cloth or plastic.

Ruler

A ruler is the instrument used to rule and calibrated stick for measurement is called a measure. However, common usage is that a ruler is calibrated so that it can be used to measure along distance markings along the edges or to measure the number of stitches.

Yardstick

A yardstick is a tool to measure distances up to three feet (a yard). Most yardsticks are flat wooden boards with black markings at regular intervals and metal tips. Many new yardsticks have imperial units markings on one side (three feet with inch and fractional inch) and metric units on the other side (one meter with centimeter and millimeter) on the reverse side.

Gauge Ruler or Knitting Needle Gauge

A gauge ruler and knitting needle measure is a handy tool for crocheters. The gauge has two measurements on it. There is a ruler to measure the crochet gauge and there are holes to determine crochet hook sizes.

Crochet Hook

A crochet hook may be used to pick up dropped stitches, for binding off stitches, or for slip stitching together knitted pieces.

Stitch Holder

A stitch holder is used to hold stitches that are to be worked later and is available in many sizes.

Cable Needle

A cable stitch holder is used to hold stitches in front or back of the work that create a cable pattern. This needle is available in various sizes and the size chosen should correspond to the knitting needle sized used on the project.

Stitch and Row Counters
Counters< are used to keep track of the row or stitch number worked.

Sewing Scissors - 5"-6" lengths

Embroidery Scissors - used for needlework and small cutting jobs

Knitting Patterns
The dictionary definition of pattern is "anything cut or formed to serve as a guide to cutting or forming objects; as, a dressmaker's pattern." Commercial knitting patterns are developed so the home knitter can create a desired garment or project with no knowledge of pattern drafting. 
(see Fiber Images™ Knitting Patterns)