Title clouds are a type of data visualization that uses words or phrases to represent the relative importance of topics. The term 'title clouds' is derived from the fact that the words used in the visualization are often taken from titles of documents, and the size of the words reflects the relative importance of the topic. The term 'LIEN' is a legal term referring to a claim on a property by a creditor. A LIEN gives the creditor the right to take possession of the property if the debt is not paid.