Barrieres

Barrieres (barriers) are objects, structures, or conditions that impede, block, or restrict movement, passage, or progress. The term is used across fields and languages, and the plural form barrieres is common in French, where the singular is barrière. In English, the standard plural is barriers.

Physical barriers include fences, walls, gates, security checkpoints, and roadblocks designed to control access or direct traffic. Fortifications, damns, and flood defenses are built to contain water or deter invasions. Natural barriers such as mountain ranges, rivers, deserts, and seas can shape civilizations by influencing settlement, trade routes, and migration.

Economic, regulatory, and social barriers are constraints that limit participation or competition. Trade barriers consist of tariffs, quotas, and export controls. Entry barriers in markets may arise from product standards, licensing requirements, or capital costs. Social barriers include language differences, cultural norms, discrimination, and unequal access to education or opportunities, which can prevent individuals or groups from participating fully in society.

In science and technology, barriers often denote thresholds that must be overcome. The activation energy barrier in chemistry describes the energy required for a reaction to proceed; a potential barrier in physics and quantum mechanics impedes particle motion, sometimes permitting tunneling under certain conditions. The blood–brain barrier in physiology restricts passage of substances from the bloodstream into the brain. Barrier concepts also appear in computing (barrier synchronization) and in design (barrier-free or accessible design, which aims to remove obstacles for people with disabilities).

Coastal geography recognizes barrier reefs, barrier beaches, and barrier islands, formations that protect shorelines by absorbing wave energy or reshaping coastal dynamics.