21 years ago I published the book Informal Economic Environments, published at the BIT Publishing House (Iasi, RO), which addressed what we considered then to be the underground economy. At that moment it was appreciated that the approach was harsh, given that "recognized personalities in the economic or journalistic field have approached such problems only in a sequential manner" (V. Codreanu, in the Preface). The same precursor notes that "Approaching the mechanisms of the underground economy and understanding their functioning is not intended to ensure its removal (perhaps, at most, its limitation), but will certainly make it easier to obtain more realistic assessments and knowledge of several aspects of it". With the sources of documentation at that time, we dealt with issues such as the identification elements of the informal economy, an overview of it, the measurement issues and the magnitude (in Romania and worldwide). When I approached the Fraud and Tax Evasion, I made a presentation of it, while also presenting the existing motivations and the extent.