Life cycle assessment or LCA (also known as life cycle analysis) is a methodology for assessing environmental impacts associated with all the stages of the life cycle of a commercial product, process, or service. For instance, in the case of a manufactured product, environmental impacts are assessed from raw material extraction and processing (cradle), through the product's manufacture, distribution and use, to the recycling or final disposal of the materials composing it (grave). An LCA study involves a thorough inventory of the energy and materials that are required across the industry value chain of the product, process or service, and calculates the corresponding emissions to the environment. LCA thus assesses cumulative potential environmental impacts. The aim is to document and improve the overall environmental profile of the product. Widely recognized procedures for conducting LCAs are included in the 14000 series of environmental management standards of the International Organization for Standardization (ISO), in particular, in ISO 14040 and ISO 14044. ISO 14040 provides the 'principles and framework' of the Standard, while ISO 14044 provides an outline of the 'requirements and guidelines'. Generally, ISO 14040 was written for a managerial audience and ISO 14044 for practitioners. As part of the introductory section of ISO 14040, LCA has been defined as the following:LCA studies the environmental aspects and potential impacts throughout a product's life cycle (i.e., cradle-to-grave) from raw materials acquisition through production, use and disposal. The general categories of environmental impacts needing consideration include resource use, human health, and ecological consequences.Criticisms have been leveled against the LCA approach, both in general and with regard to specific cases (e.g., in the consistency of the methodology, particularly with regard to system boundaries, and the susceptibility of particular LCAs to practitioner bias with regard to the decisions that they seek to inform).