This document summarizes a paper that examines the informal economy from the perspective of informal businesses. It defines the informal economy as economic activity that occurs outside the legal framework, though the activities may be legal in nature. The paper explores different views on whether the informal economy is problematic or a solution. It also discusses the size and causes of the informal economy, including how high costs of formalization can drive businesses underground. A case study on Haiti finds that most businesses operate informally there due to legislative and institutional barriers that make formalization excessively costly and complex.