Construction is a general term meaning the art and science to form objects, systems, or organizations, and comes from Latin construction (from com- “together” and structure “to pile up”) and Old French construction. To construct is the verb: the act of building and the noun is construction: how something is built, the nature of its structure.

In its most widely used context, construction covers the processes involved in delivering buildings, infrastructure and industrial facilities, and associated activities through to the end of their life. It typically starts with planning, financing, and design, and continues until the asset is built and ready for use; construction also covers repairs and maintenance work, and works to expand, extend and improve the asset, and its eventual demolition, dismantling, or decommissioning.

As an industry, construction accounts for more than 10% of global GDP (6-9% in developed countries) and employs around 7% of the global workforce – over 273m people. The output of the global construction industry was worth an estimated $10.8 trillion in 2017.

The first huts and shelters were constructed by hand or with simple tools. As cities grew during the Bronze Age, a class of professional craftsmen, like bricklayers and carpenters, appeared. Occasionally, slaves were used for construction work. In the Middle Ages, the artisan craftsmen were organized into guilds. In the 19th century, steam-powered machinery appeared, and, later, diesel- and electric-powered vehicles such as cranes, excavators, and bulldozers.

Fast-track construction has been increasingly popular in the 21st century. Some estimates suggest that 40% of construction projects are now fast-track construction.

In general, there are three sectors of construction: buildings, infrastructure, and industrial. Building construction is usually further divided into residential and non-residential. Infrastructure, also called heavy civil or heavy engineering, includes large public works, dams, bridges, highways, railways, water or wastewater, and utility distribution. Industrial construction includes offshore construction (mainly of energy installations), mining and quarrying, refineries, chemical processing, power generation, mills, and manufacturing plants.

The Standard Industrial Classification and the newer North American Industry Classification System classify companies that perform or engage in construction into three subsectors: building construction, heavy and civil engineering construction, and specialty trade contractors. There are also categories for professional services firms (e.g., engineering, architecture, surveying, project management).

Building construction is the process of adding structures to areas of land, also known as real property sites. Typically, a project is instigated by or with the owner of the property (who may be an individual or an organization); occasionally, land may be compulsorily purchased from the owner for public use.

Residential construction may be undertaken by individual land-owners (self-build), by specialist house-builders, by property developers, by general contractors, or by providers of public or social housing (eg: local authorities, housing associations). Where local zoning or planning policies allow, mixed-use developments may comprise both residential and non-residential construction (eg: retail, leisure, offices, public buildings, etc).

Residential construction practices, technologies, and resources must conform to local building authority regulations and codes of practice. Materials readily available in the area generally dictate the construction materials used (eg: brick versus stone versus timber). Costs of construction on a per square meter (or per square foot) basis for houses can vary dramatically based on site conditions, access routes, local regulations, economies of scale (custom-designed homes are often more expensive to build), and the availability of skilled tradespeople.

Depending upon the type of building, non-residential building construction can be procured by a wide range of private and public organizations, including local authorities, educational and religious bodies, transport undertakings, retailers, hoteliers, property developers, financial institutions, and other private companies. Most construction in these sectors is undertaken by general contractors.

Industrial construction includes offshore construction (mainly of energy installations: oil and gas platforms, wind power) , mining and quarrying, refineries, breweries, distilleries, and other processing plants, power stations, steel mills, warehouses, and factories.

Some construction projects are small renovations or repair jobs, where the owner may act as a designer, paymaster, and laborer for the entire project. However, more complex or ambitious projects usually require additional multi-disciplinary expertise and manpower, so the owner may commission one or more specialist businesses to undertake detailed planning, design, construction, and handover of the work. Often the owner will appoint one business to oversee the project (this may be a designer, a contractor, a construction manager, or another advisor); such specialists are normally appointed for their expertise in project delivery and will help the owner define the project brief, agree on a budget and schedule, liaise with relevant public authorities, and procure the services of other specialists (the supply chain, comprising subcontractors). Contracts are agreed for the delivery of services by all businesses, alongside other detailed plans aimed at ensuring legal, timely, on-budget, and safe delivery of the specified works.

Design, finance, and legal aspects overlap and interrelate. The design must be not only structurally sound and appropriate for the use and location, but must also be financially possible to build, and legal to use. The financial structure must be adequate to build the design provided and must pay amounts that are legally owed. Legal structures integrate design with other activities and enforce financial and other construction processes.

These processes also affect procurement strategies. Clients may, for example, appoint a business to design the project after which a competitive process is undertaken to appoint a lead contractor to construct the asset (design–bid–build); they may appoint a business to lead both design and construction (design-build); or they may directly appoint a designer, contractor and specialist subcontractors (construction management). Some forms of procurement emphasize collaborative relationships (partnering, alliancing) between the client, the contractor, and other stakeholders within a construction project, seeking to ameliorate often highly competitive and adversarial industry practices.

The output of the global construction industry was worth an estimated $10.8 trillion in 2017, and in 2018 was forecast to rise to $12.9 trillion by 2022. As a sector, construction accounts for more than 10% of global GDP (in developed countries, construction comprises 6-9% of GDP), and employs around 7% of the total employed workforce around the globe (accounting for over 273 million full- and part-time jobs in 2014). Since 2010, China has been the world’s largest single construction market. The United States is the second-largest construction market with a 2018 output of $1.581 trillion.

In the United States in February 2020, around $1.4 trillion worth of construction work was in progress, according to the Census Bureau, of which just over $1.0 trillion was for the private sector (split roughly 55:45% between residential and nonresidential); the remainder was public sector, predominantly for state and local government.

Construction is a major source of employment in most countries; high reliance on small businesses and under-representation of women are common traits. For example:

In the US, construction employed around 11.4m people in 2020, with a further 1.8m employed in architectural, engineering, and related professional services – equivalent to just over 8% of the total US workforce. The construction workers were employed in over 843,000 organizations, of which 838,000 were privately held businesses. In March 2016, 60.4% of construction workers were employed by businesses with fewer than 50 staff. Women are substantially underrepresented (relative to their share of total employment), comprising 10.3% of the US construction workforce, and 25.9% of professional services workers, in 2019.

In the United Kingdom, construction contributed £117 billion (6%) to UK GDP in 2018, and in 2019 employed 2.4m workers (6.6% of all jobs). These worked either for 343,000 ‘registered’ construction businesses or for ‘unregistered’ businesses, typically self-employed contractors; just over one million small/medium-sized businesses, mainly self-employed individuals, working in the sector in 2019, comprising about 18% of all UK businesses. Women comprised 12.5% of the UK construction workforce.

According to McKinsey research, productivity growth per worker in construction has lagged behind many other industries across different countries including in the United States and European countries. In the United States, construction productivity per worker has declined by half since the 1960s.