informal

Informal is an adjective used to describe something that is not formal or officially sanctioned. It denotes a lack of formal structure, rules, or process, or a manner of doing things that is casual or unofficial. The term is used across disciplines to indicate things operating outside formal institutions or conventions.

In language, informal or colloquial register is used in everyday speech and in casual writing. It often features contractions, slang, and personal pronouns; sentence structure tends toward simplicity. In digital communication, informal tone is common, and may include emotive expressions that would be atypical in formal contexts.

In attire, informal clothing refers to casual dress appropriate for everyday contexts, such as jeans and T-shirts, rather than suits or uniforms. Cultural norms shape what is considered informal, and the boundary between informal and smart-casual can vary by region and setting.

In economics, the informal economy or informal sector comprises activities not registered or regulated by the state, often outside labor, tax, and social-protection systems. Common examples include street vending and unregistered small-scale work. The informal sector can provide livelihoods but also entails reduced protections for workers.

Informal education covers learning outside formal schooling, including on-the-job training, community programs, mentoring, and self-directed study. It complements formal education and is a focus in development policy for expanding skills and access.

The term also appears in discussions of informal institutions, such as unwritten norms and etiquette that guide behavior without legal codification. In urban planning, informal settlements describe housing built without formal property rights or planning approval, reflecting social and economic marginalization.