A Patchwork or "pieced work" is a form of needlework that involves sewing together pieces of fabric into a larger design. The larger design is usually based on repeat patterns built up with different colored shapes. These shapes are carefully measured and cut, straight-sided, basic geometric shapes making them easy to piece together. Precise joining makes for patchwork that lies flat without puckers.

When used to make a quilt, this larger patchwork or pieced design becomes the "top" of a three layered quilt, the middle layer being the batting, and the bottom layer the backing. To keep the batting from shifting a patchwork or pieced quilt is often quilted by hand or machine using a running stitch which can outline the individual shapes that make up the pieced top, or the quilting stitches can be random or highly ordered overall patterns that contrast with the patchwork composition.

In the past hand quilting was often done in a group around a frame. Instead of quilting, the layers are sometimes tied together at regular intervals with pieces of yarn, a practice known as tying or knotting. There are three traditional structures used to construct a patchwork or pieced composition: 1) block, 2) overall, and 3) strip piecing. Traditional patchwork has identifying names based on the arrangement of colors and shapes.

Today, many quilts are quilted using a Longarm quilting system. The system consists of a frame and a sewing machine. The patchwork, batting and backing are loaded onto the frame and in some systems each layer can be tensioned independently. No basting is usually necessary. The frames can be up to 14' long which is big enough for a king size quilt to be tensioned ready for quilting. The sewing machine known as the Longarm machine has an extended throat space - up to 36" - and can be moved on a 2-axis rail system- left and right, forwards and backwards enabling a 360 degree movement over the surface of the quilt. Until recently most longarm machines were hand-guided which meant the operator had to synchronise the speed of their hands with the speed of the machine motor. Fast hands, slow motor meant big stitches. Slow hands, fast motor meant small stitches. Since just after the turn of the century most longarm machines are now sold with stitch-regulation, which means the operator no longer has to synchronise hand speed with the motor. Electronics in the machine ensures the stitch length remains constant. More recently fully computerised machines are being sold. Fully computerised machines have been available for over 12 years. They were invented by Paul Statler but have only recently become popular. These machines use specialised machine-driver software and 'cad'-type drawing packages to enable pattern digitisation and automatic quilting. An operator is still required to mind the machine and set the pattern onto the quilt. It is thought that over 10,000 longarm quilting machines are in use today. There are many brands available and many places to obtain training.

1) Patchwork blocks are pieced squares made up of colored shapes that repeat specific shapes to create patterns within the square or block, of, say, light and dark, or contrasting colors. The blocks can all repeat the same pattern, or blocks can have several different patterns . The patchwork blocks are typically around 8"-10" square. They are sewn together in stacked rows to make a larger composition. Often strips of contrasting fabric forming a lattice separate the patchwork blocks from each other. Some common patchwork block names are Log Cabin, Drunkard's Path, Bear's Paw, Tulip, and Nine Patch. A unique form of patchwork quilt is the crazy quilt. Crazy quilting was popular during the Victorian era (mid–late nineteenth century). The crazy quilt is made up of random shapes of luxurious fabric such as velvets, silks, and brocades. The patchwork pieces are stitched together forming "crazy" or non-repeat, asymmetric compositions. Fancy embroidery embellishes the seam lines between the individual, pieced shapes.

2) Overall patchwork designs are incrementally pieced geometric shapes stitched together to form a larger random or composed design. The colored shapes can be randomly pieced or follow a strict order to create a specific effect, e.g. value (light to dark) progressions, or checkerboard effects. Names such as Hit or Miss, Clamshell, back-stitch, needle weave, criss-cross and Starburst identify some overall patchwork structures.

3) Strip piecing involves stitching together pieces of fabric in repeat patterns into long strips and then stitching the strips together lengthwise. The patchwork strips can be alternated with strips of contrasting colors. A typical strip patchwork quilt is the Flying Geese pattern.

Some of the other specialized forms of patchwork are:

• Scrap Piecework
• Foundation Piecework or the closely related
• English Paper Piecework
• Seminole Piecework
• Hawaiian Piecework
• Stained glass window patchwork

Stained glass window patchwork is a type of patchwork which simulates the effect of stained glass in church windows. Satin fabrics simulate the colored glass, and black bias binding tape simulates the lead.

Patchwork enjoyed a widespread revival during the Great Depression because it was a way to recycle worn clothing into warm quilts. Even very small and worn pieces of material are suitable for use in patchwork, although crafters today more often use specially bought 100% cotton patchwork material as the basis for their designs.

Patchwork declined after World War II, but was again revived during the American bicentennial.

Patchwork is most often used to make quilts, but it can also be used to make bags, wall-hangings, warm jackets, skirts , waistcoats and other items of clothing. Some textile artists work with patchwork, often combining it with embroidery and other forms of stitchery.

The 2003 Quilting in America survey estimated that the total value of the American quilting industry was $2.7 billion. International quilting exhibitions attract thousands of visitors, while countless smaller exhibitions are held every weekend in local regions. Active cyber-quilting communities abound on the web; books and magazines on the subject are published in the hundreds every year; and there are many active local quilting guilds and shops in different countries. 'Quilt Art' is established as a legitimate artistic medium, with quilted works of art selling for thousands of dollars to corporate buyers and galleries. Quilt historians and quilt appraisers are re-evaluating the heritage of traditional quilting and antique quilts, while superb examples of antique quilts are purchased for large sums by collectors and museums. The American Quilt Study Group is active in promotion of research on the history of quilting.