ABSTRACT
Collagen is the sole most profuse protein in the animal kingdom. It has been subjected to various studies from time immemorial. Its applications are numerous and have been extracted from various sources such as land animals (mainly bovine and porcine) and birds. Although collagen sources are abundant the outbreak of varied diseases among land animals posed a threat to its utilization in our daily life. Thus a probe for an alternative source began which in turn revealed the immense untapped marine source. The present article deals with a brief description of collagen its characteristics,chemistry,common extraction procedure, application in various fields and sources. A lot of studies have been carried out on various land animals, birds and marine organisms and this review sums up the work performed to date in a concise manner.