What Is an Industry
An industry is a group of companies that produce similar goods or services and compete in the same market. Economists classify industries by inputs, outputs, and business models to compare performance and risk. Standard systems include the Global Industry Classification Standard (GICS) and the North American Industry Classification System (NAICS). These codes help investors, regulators, and analysts group firms into sectors and subsectors for research and reporting. For background on classification systems, see the U.S. Census Bureau overview of NAICS here.
Industries are measured by revenue, employment, market capitalization, and trade flows. The World Bank and International Monetary Fund publish data on industry value added and output by country. In recent years, digital services, electric vehicles, and renewable energy have grown faster than traditional manufacturing in many economies. Companies such as Tesla and SpaceX operate in industries that combine hardware, software, and services, reflecting modern cross-sector business models.
Major Industry Sectors and Examples
The broadest classification divides the economy into primary, secondary, and tertiary sectors. Primary industries include agriculture, mining, and oil and gas extraction. Secondary industries cover manufacturing, construction, and utilities. Tertiary industries include finance, healthcare, education, and professional services. The Global Industry Classification Standard organizes public companies into 11 sectors, such as energy, financials, health care, information technology, and consumer discretionary.
Technology and Digital Services
The technology sector includes software, semiconductors, cloud computing, and internet platforms. In 2024, the global semiconductor market reached roughly $600 billion, driven by demand for artificial intelligence chips and data center equipment. Companies like NVIDIA, TSMC, and Advanced Micro Devices are among the largest suppliers of processors and GPUs used in AI training and inference. For more on semiconductor market trends, see the Semiconductor Industry Association here.
Energy and Automotive
Traditional energy industries include oil and gas extraction, refining, and petrochemicals, while the automotive sector now spans internal combustion engines, electric vehicles, and battery supply chains. Tesla is one of the most valuable automakers by market capitalization, with factories in the United States, China, and Germany. SpaceX operates in aerospace and launch services, competing with government space agencies and other commercial providers.
How Industries Are Measured and Ranked
Industry size is often reported as total revenue, market capitalization, or value added. Rankings typically list the largest companies by revenue or market cap within each sector. Forbes and Fortune publish annual lists such as the Global 2000 and Fortune 500, which rank public companies by revenue, profits, assets, and market value. These lists help investors compare industry leaders and track shifts in economic power across sectors.
Regulators also monitor industries for competition, stability, and systemic risk. In the United States, the Securities and Exchange Commission requires public companies to file annual reports and disclosures that include financial and operational details by segment. The SEC EDGAR database provides free access to these filings, enabling analysts to compare companies within the same industry here. For a broader view of industry performance, the Bureau of Economic Analysis publishes data on gross domestic product by industry here.