The "informal economy" refers to all economic activities by workers and economic units that are - in law or in practice - not covered or insufficiently covered by formal arrangements". Informality poses serious challenges to workers (decent work deficits, poverty and vulnerability), economic units (low productivity and lack of access to finance and markets) and Governments (issue of governance and rule of law, limited fiscal space). In many countries, informal employment and informal sector economic units represent a significant part of the economy and labour market and plays a major role in production, employment creation and income generation. The debate concerning strategies towards formalization of the informal economy gained new momentum worldwide, after ILO's constituents adopted, at the International Labour Conference in June 2015, the Recommendation 204 (R204), the first international standard focusing exclusively on the informal economy and the strategies to adopt for the transition from the informal economy to the formal economy. This new instrument constitutes a historic landmark, not only to ILO constituents but also to all those who are concerned with inclusive development, poverty eradication, and reducing inequalities. R204 is an operational tool towards the achievement of the new Sustainable Development Goals (SDGs) where formalization is within the key indicators of Goal 8 - to promote sustained, inclusive and sustainable economic growth, full and productive employment and decent work for all. Measuring and analysing informality remains a challenge for many developing countries that hinders policy-making, as the informal economy's economic contribution is missing due to the lack of data and statistics concerning the informal economy. Bearing in mind the growing demand from countries to better understand the functioning of the informal economy and the measurement of informality, the International Training Centre of the ILO in Turin (ITCILO) in close collaboration with the ILO Department of Statistics are proud to offer this E-Learning course "Measuring Informality".