In knitting

Knitting

Knitting is a method by which thread or yarn may be turned into cloth or other fine crafts. Knitted fabric consists of consecutive rows of loops, called stitches. As each row progresses, a new loop is pulled through an existing loop. The active stitches are held on a needle until another loop can...

, a bobble is a localized set of stitches forming a raised bump. The bumps are usually arranged in a regular geometrical pattern (e.g., a hexagonal grid) or may be figurative, e.g., represent apples on a knitted tree.

The basic idea of a bobble is to increase into a single stitch, knit a few short rows

Short row (knitting)

In knitting, a short row is a row that is not fully knitted; the work is turned before reaching the end of the row. Just before the work is turned, the yarn is generally passed around the next unknitted stitch to prevent a hole from forming at the turning point.The typical bobble provides a simple...

, then decrease back to a single stitch. However, this leaves many choices: how to increase and how many stitches, how many short rows to work, and how to decrease.

A bobble can also be a yarn Pom-pon

Pom-pon

A pom-pon is a fluffy, decorative ball or tuft. Pom-pons may come in many colors, sizes, and varieties and are made from a wide array of materials, including wool, cotton, paper, plastic, and occasionally feathers....

 used to decorate knitted items such as Bobble hat

Bobble hat

A Bobble hat or Bobble cap is a colloquial term for a knit beanie or tuque trimmed with a yarn "bobble" or pom-pom upon the crown. Bobble hats are generally considered utilitarian cold weather wear...

s.