The term building contractors may be applied to those involved in construction management and tactical (hands on) construction, or more broadly to include those folks involved in the design and planning stages of a project. Building contractors handle residential and commercial construction and are somewhat regulated when you consider the licensing and insurance requirements which vary by specific trade and by state and locale.
Construction delivery comes in two main forms. Design-bid-build common to government contracts is the process by which an architect is selected to prepare draft documents which are then passed along to pre-select or competing general contractors. Design-build seeks to deploy both design and construction aspects into one free flowing entity such as a design-build contractor or general contractor.
Construction bidding is the process by which a proposal is submitted to perform a construction project and most are highly detailed and will include estimate labor and input (material costs) in order to be competitive. Bids are facilitated by government entities or data services and charge subscriptions or flat fees on individual bids to participating building contractors. Building contractors should understand and seek to avoid low bid contracts that seek to win work. Low bids are obvious and typically passed over in bid selection as they pose insolvency risk to the project owner or entity or worse can run way over budget.
Nationwide there are organizations whose primary purpose is to organize and to some extent formalize the construction industry. One such organization is the Associated General Contractors of America (AGC). The AGC dates back to the 1700s and is considered one of the oldest trade organizations in the country.