Life Cycle Assessment (LCA) is a systematic approach used to evaluate the environmental impact associated with all phases of a product, process, or service's life cycle. It encompasses everything from the extraction of raw materials to production, distribution, usage, and disposal. LCA involves a comprehensive inventory of energy and materials throughout the supply and value chains, calculating corresponding emissions and environmental impacts. Its objective is to document and enhance the overall environmental profile of a product, providing a basis for comparing carbon footprints accurately. ISO 14040 and ISO 14044 are widely recognized standards for conducting LCAs, outlining principles, framework, requirements, and guidelines.

LCA considers environmental aspects and potential impacts throughout a product's life cycle, including resource use, human health, and ecological consequences. Despite its standardization efforts, LCA methodologies may face criticisms regarding consistency, cost, and the influence of practitioner perspectives or sponsoring entities' interests. LCA, also known as 'cradle-to-grave' analysis aims to assess environmental consequences across all stages of a product's life cycle to avoid sub-optimization. It facilitates decision-making by quantifying material flows' inputs and outputs and assessing their environmental impact comprehensively.

Attributional LCA attributes burdens associated with a product or service's production and use over a defined temporal period, while Consequential LCA identifies environmental consequences of decisions and incorporates market and economic considerations. Social Life Cycle Assessment (SLCA) evaluates social impacts on stakeholders such as workers and local communities, following UNEP/SETAC guidelines. While LCA focuses on ecological aspects, methods like product line analysis (PLA) consider economic and social factors.

ISO 14040 and 14044 define four phases of LCA: Goal and Scope, Inventory Analysis, Impact Assessment, and Interpretation. Each phase informs the subsequent stages, with none considered finalized until the entire study is completed. In summary, LCA provides a comprehensive methodology to evaluate the environmental impact of products, processes, or services, aiming to inform sustainable decision-making by considering the full spectrum of environmental effects throughout their life cycles.