All organisms go though stages in life called life cycles. When born, animals grow to be adults. These young adults mate, and the females lay new eggs or give birth. This is called a life cycle. New members of a group are born; they grow to mature creatures; they mate and have babies; then they get old and die.

Plants start life as seeds or spores, usually growing in a simple form before becoming fully distinguished into stem, leaves and flowering parts. The flowering parts generate the seeds which

Some organisms have distinct stages of development. Butterflies and Moths start as an egg, go to a caterpillar then become a pupa before emerging as beautiful winged creatures. Many fish have distinct stages too. Salmons start as eggs, go through young stages called "alevins", then becoming "fingerlings" which start migrating down rivers often across thousands of miles, before returning home as a full the adult.

You can say humans start as children, become teenagers before becoming adults and then old age pensioners. Every organism goes through similar stages in their cycle. The stages of growth can be retraced through the embryo, often showing forms (e.g gills) that have been lost along the way to our present states.

Birth and death are part of the life cycle. One death creates the conditions for the next life. In nature, we see the process of birth through function to death and the return to earth. This process of regeneration from seed to plant to soil forms a "closed circle" where resources are continuously replenished.

We can apply the idea of a "life-cycle" to work. The life-cycle concept is a "cradle to grave" approach to examine products, processes and services. "Product Life Cycle analysis" recognizes that all product life-cycle stages (extracting and processing raw materials, manufacturing, transportation and distribution, use/reuse, and recycling and waste management) have environmental and economic impacts..

The life-cycle approach applies to all of the upstream and downstream functions of any site. This differs from more specific "end of pipe" or "within the plant gate" approaches of more limited environmental management.

Life-cycle assessment or analysis (LCA) examines the total environmental impact of a product through every step of its life - from obtaining raw materials (for example, through mining or logging) all the way through making it in a factory, selling it in a store, using it in the home, and disposing of it.

" Life Cycle Assessment (LCA) is a technique for assessing the potential environmental aspects and potential aspects associated with a product (or service), by: · compiling an inventory of relevant inputs and outputs, · evaluating the potential environmental impacts associated with those inputs and outputs, · interpreting the results of the inventory and impact phases in relation to the objectives of the study."

ISO Committee Draft 14040.3 draft on LCA, October 1995