Yarn bombing is the act of creating knitted or crocheted works of art and presenting the yarn creation in a public setting by wrapping and securing it around a tree, a lamp post, a bicycle rack, etc.  Yarn bombing is also known as yarn storming, guerrilla knitting and urban knitting.  The act of yarn bombing can be seen as a way to bring some warmth and personality to an otherwise utilitarian and ordinary public setting.

This photo is an example of yarn bombing in my particular part of the city.  Someone has knitted this cheerful lamp post cozy.  It has stayed on this lamp post for years through rain and shine, and the colors are still vibrant.  It adds a human and unique touch to this street corner.  I love random acts of creative art!

Clicking on the link provided below will take you to Wikipedia which explains in more detail the meaning and origins of yarn bombing.

http://en.wikipedia.org/wiki/Yarn_bombing