Shell companies are corporations formed without significant assets or operations, mainly existing on paper. They are used for money laundering, tax evasion, fraud, and financing terrorism. A 2011 World Bank study found the US ranked number 1 for shell companies used by corrupt officials due to lax incorporation laws in states like Delaware and Nevada that allow anonymous ownership. Investigative journalists use tools like business registries and online databases to research shell companies and uncover hidden wrongdoing.