A trust or corporate trust is a large grouping of business interests with significant market power, which may be embodied as a corporation or as a group of corporations that cooperate with one another in various ways. These ways can include constituting a trade association, owning stock in one another, constituting a corporate group, or combinations thereof. The term trust is often used in a historical sense to refer to monopolies or near-monopolies in the United States during the Second Industrial Revolution in the 19th century and early 20th century. The use of corporate trusts during this period is the historical reason for the name "antitrust law".

Competition law is the field of law that promotes or seeks to maintain market competition by regulating anti-competitive conduct by companies. Competition law is implemented through public and private enforcement. It is also known as antitrust law, anti-monopoly law, and trade practices law; the act of pushing for antitrust measures or attacking monopolistic companies is commonly known as trust busting.